JP2001338408A - Magnetic head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magneto-resistance effect sensor in which a tunnel magneto-resistance effect film is used and Barkhausen noise is restrained and which has stability and to provide a reproducing head and a magnetic recording/ reproducing device using the magneto-resistance effect sensor. SOLUTION: This magneto-resistance effect sensor is provided with the tunnel magneto-resistance effect film, a pair of electrodes 18 for making an electric current pass through the magneto-resistance effect film in the film thickness direction and a magnetic flux guide 14 for guiding a magnetic flux from a recording medium face to the magneto-resistance effect film. In this sensor both the magnetic domain in the free layer of the tunnel magneto-resistance effect film and that in the magnetic flux guide are controlled at the same time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head and a magnetic recording / reproducing apparatus. In particular, the present invention relates to a tunnel magnetoresistance effect type magnetic head and a magnetic recording / reproducing apparatus using the same. The magnetic recording / reproducing apparatus of the present invention is useful for an electronic computer and an information processing apparatus.

[0002]

2. Description of the Related Art With the increase in density of magnetic recording, a magnetic head for reproduction with high sensitivity is required. For such applications, a magnetoresistive effect type magnetic head (MR head) utilizing an anisotropic magnetoresistance (AMR) effect is currently used as the reproducing head. The material of the magneto-sensitive part of this MR head is Ni
Fe is used. The magnetoresistance ratio of this material is about 2%, and the achievable recording density is several Gb / in ² .
Further, recently, a spin valve magnetic head (GMR head) utilizing a giant magnetoresistance (GMR) effect has begun to be used in products. This GMR head has a structure in which a nonmagnetic metal layer is sandwiched between two ferromagnetic layers. In this structure, the magnetization of one ferromagnetic layer is fixed, and a high magnetoresistance ratio can be obtained depending on the angle between the magnetization directions of the two ferromagnetic layers. The resistance change rate of the GMR head was about 4 to 5%, and recording of several tens of Gb / in ² class became possible. However, in order to further improve the recording density in the future, a magnetic head having a larger magnetoresistance change rate is required.

As a magnetoresistive sensor having such a high magnetoresistance change rate, a magnetoresistive film (TMR) using a tunnel magnetoresistive film in which a tunnel barrier layer is sandwiched between two ferromagnetic layers is known. Attention has been paid. A magnetoresistive film using this tunnel magnetoresistive film is considered to be suitable for realizing high-density recording. In this TMR, F
The structure is such that an Al oxide film is sandwiched between e-films.
It is reported that a large rate of change in resistance was obtained. This report includes, for example, Journal of Magnetics and Magnetic Materials (13th Edition).
9, 231, 1995).
Japanese Patent Application Laid-Open No. 4-103014 discloses a spin valve type TMR in which an antiferromagnetic layer is in contact with one ferromagnetic layer to fix the magnetization direction of the ferromagnetic layer.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetoresistive sensor using a tunnel magnetoresistive film, which suppresses Barkhausen noise and is stable. . Hereinafter, the background will be described.

In the case of TMR, a conventionally known magnetoresistive effect element has a configuration in which a current flows in a film thickness direction while a current flows in an in-plane direction of a magnetic film. It is considered that a magnetic head structure different from the conventional one is required to realize this configuration. On the other hand, the TMR magnetically has two ferromagnetic layers similar to the spin valve structure developed conventionally, and magnetic control of these ferromagnetic layers is naturally required. Further, since current flows in the film thickness direction, the element resistance is determined by the size of the element.

For example, in a hard bias structure similar to a conventional magnetoresistance effect element, a hard magnetic film for controlling magnetic domains is arranged around the element. Therefore, when this structure is used in TMR, current leaks to the hard magnetic film, and TMR
It becomes difficult to accurately apply a current to the magneto-sensitive part of the MR. Further, an extremely thin tunnel barrier layer is exposed in the magnetic sensing portion of the TMR. Therefore, in order to prevent a short circuit between the two ferromagnetic layers in processing the opposing surface, extremely difficult processing technology is required. Further, when the track width is reduced to about 0.5 μm, the resistance of the element is increased by several hundreds to several kΩ.

[0007]

In order to solve the above-mentioned conventional problems, it is effective to adopt a structure in which the structure is retracted from the opposing surface instead of a structure which is exposed in the conventional opposing surface.
However, in this case, in addition to the ferromagnetic layer of the magnetic sensing portion of the TMR, magnetic control of a magnetic flux guide for guiding a magnetic flux to the TMR from the medium facing surface is naturally required. The present invention solves this problem as well.

In the first embodiment of the present invention, the basic form is a magnetoresistive film, a pair of electrodes for flowing a current in the thickness direction of the magnetoresistive film, and a magnetic flux from the recording medium surface. To the magnetoresistive film, the magnetoresistive film having a free layer including a ferromagnetic layer, a tunnel barrier layer, a fixed layer including a ferromagnetic layer, and a magnetization of the fixed layer. And a magnetoresistive sensor having an antiferromagnetic layer for fixing the magnetic field of the tunnel type magnetoresistive film and a magnetic domain of both the free layer and the magnetic flux guide. A magnetic head characterized in that:

A typical example of the present invention is that the free layer of the tunnel magnetoresistive film and the magnetic domain control layer for applying a bias to the magnetic flux guide for controlling the magnetic domain of the magnetic flux guide are flush with each other. It is a form provided inside.

Another example of the present invention is a magneto-resistance effect film,
In a magnetoresistive sensor having a pair of electrodes for flowing a current in the thickness direction of the magnetoresistive film and a magnetic flux guide for guiding a magnetic flux from a recording medium surface to the magnetoresistive film, The effect film is a tunnel type magnetoresistive film including a free layer including a ferromagnetic layer, a tunnel barrier layer, a fixed layer including a ferromagnetic layer, and an antiferromagnetic layer for fixing the magnetization of the fixed layer. A magnetic domain control layer formed at a position where the magnetoresistive effect film is not exposed to the medium surface, in contact with the magnetic flux guide extending from the medium surface to the opposing surface, and for applying a bias magnetic field to the magnetic flux guide. The magnetic head is characterized in that it has a magnetoresistive sensor that is stacked and that can control the magnetic domain of the free layer at the same time by controlling the magnetic domain of the magnetic flux guide.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Prior to describing the embodiments, the outline of the main embodiments of the present invention will be listed.

The basic form of the first embodiment of the present invention has been described above.

The configuration of the magnetoresistive sensor is roughly divided into two methods, that is, a method of controlling the magnetic domain of the magnetic flux guide. They are a so-called hard bias structure and a laminated structure. However, it goes without saying that the present invention can be applied to the magnetoresistive sensor having any structure.

Although these structures on which the present invention is based are known so far, their features will be briefly described. In the hard bias structure, a method of arranging magnetic domain control layers at both ends of the magnetic flux guide, that is, a so-called magnetic flux guide (yoke) and the magnetic domain control layer are arranged in the same plane. In this case, the magnetic domain control layer is made of a material having high resistance. Therefore, the current flows only in a predetermined limited region, that is, flows in a region of only a predetermined tunnel type magnetoresistive film. On the other hand, in the laminated structure, a magnetic flux guide and a magnetic domain control layer are laminated. In this case, there is a method of directly laminating a magnetic domain control layer on the magnetic flux guide, or a method of laminating a magnetic domain control layer on the magnetic flux guide via an intermediate layer. In the case of direct lamination, the magnetic flux guide and the magnetic domain control layer are ferromagnetically interlayer-coupled, and the magnetization directions are parallel. Further, when a magnetic domain control layer is laminated on the magnetic flux guide via an intermediate layer, depending on how the intermediate layer is provided,
It can be divided into two states. The first is a case where the magnetic flux guide and the magnetic domain control layer are ferromagnetically interlayer-coupled and the magnetization directions are parallel. This structure is similar to the above-mentioned stacked type. Alternatively, it can be said to be a variation of the above-mentioned laminated type. The second is a case where magnetostatic coupling is performed at the end of the magnetic flux guide and the magnetic domain control layer. Therefore, in this case, the directions of the in-plane magnetizations of the magnetic flux guide and the magnetic domain control layer are antiparallel. As described above, in the first and second embodiments of the laminated structure, the method of determining the direction of magnetization of the magnetic flux guide and the magnetic domain control layer is different.

The gist of the present invention lies in controlling the magnetic domain of the magnetic flux guide and controlling the magnetic domain in combination with the free layer of the magnetoresistive film regardless of these structures. Less than,
The concept will be described.

FIG. 12 is a conceptual diagram for explaining the above-described various embodiments, and shows cross sections showing various examples of the arrangement of the magnetic flux guide and the magnetic domain control layer. The cross section is a cross section in the width direction of the magnetoresistive element. FIG. 12 shows the concept of three typical modes. FIG. 12A shows a method of arranging magnetic domain control layers at both ends of a magnetic flux guide. The magnetic domain control layer 101 of the so-called magnetic flux guide 100 is arranged in the same plane. FIG. 12B shows an example in which the magnetic flux guide 100 and the magnetic domain control layer 101 are stacked. In this case, an extremely thin intermediate layer may be inserted between the magnetic flux guide 100 and the magnetic domain control layer 101. In these examples, as described above, the magnetic flux guide and the magnetic domain control layer are ferromagnetically interlayer-coupled, and both magnetization directions 104 and 105 are oriented in parallel. On the other hand, FIG.
FIG. 2C shows an example in which the magnetic flux guide 100, the intermediate layer 108, and the magnetic domain control layer 101 are stacked. This is a case where magnetostatic coupling is performed at ends 102 and 103 between the magnetic flux guide and the magnetic domain control layer. In this case, the directions 106 and 107 of the in-plane magnetizations of the magnetic flux guide and the magnetic domain control layer are antiparallel.

FIG. 13 is a cross-sectional view for explaining the outline of magnetic domain control of the TMR. Also in these relations, the case where the magnetic flux guide 100 and the TMR film 110 are directly laminated (FIG. 13A) and the case where the intermediate layer 111 is inserted therebetween (FIG. 13B )). However, in each case, the magnetic flux guide 100 and the TMR
There is a magnetic coupling with the film 110. Therefore, by controlling the magnetic domains of the magnetic flux guide 100, the magnetic domains of the free layer in the TMR film are controlled. Thus, in the present invention, the magnetic domain of the magnetic flux guide is controlled by the magnetic domain control film, whereby T
The magnetic domains of the free layer in the MR film are also controlled.

Based on the above general description, further main modes of the present invention will be listed. According to a second aspect of the present invention, there is provided a magnetoresistive film, a pair of electrodes for passing a current in the thickness direction of the magnetoresistive film, and a magnetic flux from a recording medium surface to the magnetoresistive film. The magnetoresistive film has a free layer including a ferromagnetic layer, a tunnel barrier layer, a fixed layer including a ferromagnetic layer, and an antiferromagnetic layer for fixing the magnetization of the fixed layer. A magnetic domain control layer for applying a bias magnetic field to a free layer of the magnetoresistive effect film, and a magnetic domain control layer for applying a bias magnetic field to the magnetic flux guide. A magnetic head having a magnetoresistive sensor formed therein. This second form is
This is a method in which magnetic domain control layers are arranged at both ends of a magnetic flux guide.

The third form is more practical. That is, in the magnetoresistive effect sensor in this case, the magnetoresistive effect film is formed at a position not exposed to the medium surface, contacts the magnetic flux guide extending from the medium surface to the opposing surface, and Magnetic domain control layers are formed at both ends of the magnetic flux guide in the track width direction.

A fourth embodiment is an example in which the magnetic flux guide is separated into the magnetoresistive film on the medium surface side and the opposing surface side.

A fifth embodiment is a magnetic head characterized in that the magnetic flux guide has a magnetoresistive sensor formed continuously from the medium surface side of the magnetoresistive film to the opposing surface.

In a sixth mode, an intermediate layer is disposed between the magnetic flux guide and the free layer of the magnetoresistive film.
A magnetic head comprising a magnetoresistive sensor in which the magnetic flux guide and the free layer are magnetically coupled via an intermediate layer.

A seventh aspect is a magnetic head characterized in that the magnetic flux guide has a magnetoresistive sensor made of a high-resistance soft magnetic layer.

An eighth aspect is a magnetic head having a magnetoresistive sensor in which the magnetoresistive film and the magnetic flux guide are formed via an insulating layer.

A ninth embodiment is a magnetic head characterized in that the magnetic domain control layer has a magnetoresistive sensor formed over the magnetoresistive film and the magnetic flux guide.

A tenth embodiment is a magnetic head characterized in that the magnetic domain control layer has a magnetoresistive sensor formed over the magnetoresistive film and the magnetic flux guide via an insulating layer.

An eleventh aspect is a magnetic head characterized in that the magnetic domain control layer has a magnetoresistive sensor having an oxide compound.

The twelfth form is an example of the form of the laminated structure already mentioned. The gist of this example is formed at a position where the magnetoresistive film is not exposed to the medium surface, is in contact with the magnetic flux guide extending from the medium surface to the opposing surface, and applies a bias magnetic field to the magnetic flux guide. A magnetic domain control layer is laminated. In this case, by controlling the magnetic domain of the magnetic flux guide, the magnetic domain of the free layer is controlled at the same time. More specifically, the structure is shown as follows: a magnetoresistive film, a pair of electrodes for flowing a current in the thickness direction of the magnetoresistive film, and a magnetic flux from a recording medium surface to the magnetoresistive film. In the magnetoresistive sensor having a magnetic flux guide, the magnetoresistive film has a free layer including a ferromagnetic layer,
A tunnel-type magnetoresistive film including a tunnel barrier layer, a fixed layer including a ferromagnetic layer, and an antiferromagnetic layer for fixing the magnetization of the fixed layer, wherein the magnetoresistive film is exposed on a medium surface. A magnetic domain control layer for applying a bias magnetic field to the magnetic flux guide is formed in contact with the magnetic flux guide formed at a position where the magnetic flux guide does not extend and extending from the medium surface to the opposing surface, and controls the magnetic domain of the magnetic flux guide. The magnetic head is characterized in that the free layer has a magnetoresistive sensor capable of controlling the magnetic domain at the same time.

According to a thirteenth aspect, in the magnetoresistive sensor of the twelfth aspect, there is provided a magnetoresistive sensor in which the magnetic flux guide and the magnetoresistive film are magnetically coupled via an intermediate layer. A magnetic head characterized in that:

A fourteenth embodiment is characterized in that, in the twelfth and thirteenth magnetoresistive sensors, the magnetic flux guide and the magnetic domain control layer are laminated with an intermediate layer interposed therebetween. Magnetic head.

In the above structure, the magnetic flux guide and the magnetic domain control layer are magnetically coupled. Therefore, the magnetic domain control layer controls the magnetic domain of the magnetic flux guide, and also controls the magnetic domain of the free layer of the magnetoresistive film.

According to a fifteenth aspect, in the twelfth to fourteenth magnetoresistive sensors, the magnetic flux guide is separated into a medium surface side of the magnetoresistive film and an opposing surface thereof. A magnetic head having a sensor. This example is a more practical form.

According to a sixteenth aspect, in the magnetoresistive sensor according to any one of the twelfth to fourteenth aspects, the magnetic flux guide is formed continuously from the medium surface side to the opposing surface of the magnetoresistive effect film. A magnetic head having a resistance effect sensor.

According to a seventeenth aspect, in the magnetic head according to the twelfth to sixteenth magneto-resistance effect sensors, the magnetic flux guide includes a magneto-resistance effect sensor having a high-resistance soft magnetic layer. is there.

A recording / reproducing head can be constituted by using the various magneto-resistive sensors enumerated above as a reproducing element. Further, a magnetic recording / reproducing apparatus can be configured by mounting such a recording / reproducing head. These recording / reproducing heads or magnetic recording / reproducing devices have sufficiently small signal noise. Therefore, the recording / reproducing head or the magnetic reproducing / recording apparatus according to the present invention can obtain extremely stable recording / reproducing characteristics.

The basic structure of the magnetoresistive reproducing head itself is usually sufficient. That is, in a typical mode, a lower magnetic shield made of a magnetic material, a lower interlayer insulating film, a magnetoresistive element for detecting a magnetic field by a magnetoresistance effect, and an upper magnetic shield made of an upper interlayer insulating film and a magnetic material are formed on a substrate. Is formed.

FIG. 10 is a perspective view of a main part of the magnetic recording / reproducing head according to the present invention. Referring to the example of FIG. 10, a magnetic recording / reproducing head is arranged to face the sliding surface of the magnetic disk 53. It should be noted that reference numeral 64 in the drawing indicates a state of magnetic recording on a recording medium of a magnetic disk as a model. The slider 61 forms a substrate, on which a magnetoresistive element is arranged. That is, the magnetoresistive film (TMR film) 13 is mounted on the lower magnetic shield 65. Then, the insulating film 67
, A lower magnetic core 66 is arranged. Reproduction head 1
Numeral 3 is sandwiched between the first shield 67 and the second shield film 65, and has a structure in which a leakage magnetic field from the surroundings is cut off to make it easy to reproduce only information directly below the target. I have.
The lower magnetic core 66 also has a role as an upper magnetic shield and an electrode. Further, the exciting coil 63
An upper magnetic core (recording head) 62 is arranged with the.
One surface on which the first magnetic pole 66, the insulating film, and the second magnetic pole (recording magnetic pole) 62 are stacked constitutes a sliding surface. The insulating film forms a recording gap.

FIG. 7 is a schematic explanatory view of an example of the magnetic recording / reproducing apparatus according to the present invention. A magnetic disk 53 on which information is recorded is rotated by a spindle motor 54. A slider 55 is arranged facing the sliding surface of the magnetic disk 53. The slider 55 has a built-in magnetic recording / reproducing unit. The magnetic recording / reproducing unit and the like are controlled by a signal processing unit 57. The signal processing unit 57 contains, for example, an electrical control system such as a data reproduction / decoding system or a mechanism control system. A mechanism control system, a slider, and the like are connected to the actuator 56. The electric system for signal processing, rotation control, and the like of such a magnetic recording / reproducing apparatus is basically sufficient using conventional techniques. Here, the detailed description is omitted.

Embodiment 1 FIG. 1 is a perspective view of a main part of a magnetoresistive sensor 20 according to a first embodiment. As shown in FIG. 1, a lower magnetic shield film 11, a lower gap film 12, a tunnel magnetoresistive film (hereinafter, this film is referred to as a TMR film (Tu
nnellingMagnetoresistive L
13, a magnetic flux guide 14, a magnetic domain control film 15, an upper gap film 16, and an upper magnetic shield film and lower magnetic core 17 are sequentially formed. Usually, as shown in the figure, the upper magnetic shield film 17 and the lower magnetic shield film 11 each have a lead electrode terminal portion 18 and also serve as an electrode for flowing a current in the thickness direction of the TMR film 13. ing. Details of the cross section of this magnetoresistive sensor are shown in FIGS. 2A and 2B.

When the azimuth of the magnetoresistive sensor is defined as a track width direction 101, an element height direction 102, and a magnetic head driving direction 103, the cross sections taken along line A and line B in FIG. And track width direction 101
2 shows a cross section parallel to FIG. FIG. 2A is a sectional view parallel to the element height direction 102 of the magnetoresistive effect sensor 20, and FIG. 2B is a sectional view parallel to the track width direction 101. FIG. 11 is a plan view of the magnetoresistive effect sensor 20. Lower magnetic shield film 11 and lower gap film 12 on substrate 10
Are formed in a desired shape. On a part of the lower gap film 12, a TMR film 13 is arranged at a position away from the air bearing surface. A set of magnetic flux guides 14 is mounted on the end of the TMR film 13 so as to extend from the air bearing surface side in the element height direction (102). Magnetic flux guide 1
Reference numeral 4 denotes a soft magnetic film for guiding magnetic flux from the medium to the TMR film 13. Specifically, the TMR film 13 includes, for example, a base film 21, an antiferromagnetic film 22, a first ferromagnetic film (referred to as a fixed layer) 23, a tunnel barrier layer 24, a second ferromagnetic film It has a film (referred to as a free layer) 25. The in-plane magnetizations of the free layer 25 and the fixed layer 23 are oriented in a direction inclined by 90 degrees with respect to each other in a state where no external magnetic field is applied. The magnetization of the fixed layer 23 is fixed in a preferable direction by the antiferromagnetic film 22. In the sense that the in-plane magnetization is fixed, the first ferromagnetic film 23 is called a fixed layer. On the other hand, the magnetization of the free layer 25 is freely rotated by the magnetic field passing through the magnetic flux guide 14 from the medium. Then, a resistance change occurs due to the rotation of the magnetization, and an output of the element is generated. The second ferromagnetic film 25 is called a free layer in the sense that the in-plane magnetization rotates freely.

As can be seen from FIG. 11, a magnetic domain control film 15 is provided on both sides of the TMR film 13 in the sliding direction.
Magnetic flux guides 14 are arranged on both sides of the film 13 in a direction intersecting the sliding surface 200.

In the present embodiment, in order that the current flowing through the TMR film 13 does not leak to the magnetic flux guide 14 and the magnetic domain control film 15, both of them must have higher resistance than the TMR film 13.

As shown in FIG. 2B, on both sides of the TMR film 13 and the magnetic flux guide 14 in the track width direction 101,
The magnetic domain control films 15 are respectively arranged so as to ride on both ends. The magnetic domain control film 15 is a ferromagnetic film that applies a bias magnetic field to suppress the generation of magnetic domains in the magnetic flux guide 14 and the free layer 25.

An upper gap film 16 and an upper magnetic shield film 17 are formed on the TMR film 13, the magnetic flux guide 14 partially overlapped with the TMR film 13, and the magnetic domain control film 15. The upper gap film 16 is in contact with the TMR film 13 only at the through hole 19. Both sides of the through hole 19 are constituted by the magnetic flux guide 14 and the magnetic domain control film 15. Each of the lower magnetic shield film 11 and the upper magnetic shield film 17 has a lead electrode terminal portion 18. By the connection of the electric terminals, application of current and detection of reproduction output are performed. When a current is applied to the electrode terminal portion 18, the current passes through the through-hole 19 and T
It flows only to the MR film 13.

Next, examples of various materials will be specifically described.

The lower magnetic shield film 11 itself is sufficient to use a usual material, but if a suitable material is used, a Co-based amorphous alloy such as CoNbZr, a NiFe alloy, a FeAlSi alloy, a CoNiFe alloy, or the like can be used. Can be raised. The thickness of the lower magnetic shield film 11 is approximately 1 to 5 μm. For the upper magnetic shield film 17 itself, it is sufficient to use a usual material, but if a suitable material is used, a NiFe alloy or CoNi
In addition to the Fe alloy, a multilayer film of a ferromagnetic film and an oxide, a ferromagnetic alloy film containing a semimetal such as B or P, and the like can be given. This upper magnetic shield film 17 can also serve as the lower core of the recording magnetic head.

Since the lower gap film 12 serves as a base film of the TMR film 13, it is desirable that the surface of the lower gap film 12 is smooth and clean so that the characteristics of the TMR film 13 are stable and the resistance change amount is high. If a material suitable for the lower gap film 12 is used, for example, Ta, Nb, Ru, Mo, Pt, Ir, or an alloy containing these elements, or an alloy with W, Cu, Al, or a different element And a multilayer structure. Examples of the multilayer structure composed of the different elements are, for example, Ta / Pt / Ta and Ta / Cu / Ta. It goes without saying that a stack of the various elements can be used.

As the lower gap film 12, the above-listed elements, for example, Ta, Nb, Ru, Mo, Pt, Ir, or an alloy containing these elements, or an alloy with W, Cu, Al,
Further, a stacked structure of a multilayer structure including different elements and a ferromagnetic material can be used. This example is Ta / Ni
Fe. The thickness of the lower gap film 12 is approximately 3 nm.
３０30 nm. Usually, the thickness of the lower gap film 12 is set to a desired value depending on the distance between the lower magnetic shield film 11 and the upper magnetic shield film 17. Upper gap film 1
6 is the same material as the lower gap film 12, or
It is formed of Au, Al, or the like. Base film 21 is antiferromagnetic film 2
2 to increase the coupling magnetic field. Underlayer 2
Examples of materials suitable for (1) include Ta, NiFe, or a laminated film of these materials, Ta / NiFe.

Examples of materials suitable for the antiferromagnetic film 22 include MnIr, MnPt, FeMn, CrMn-based alloy, MnPtPd, and NiMn-based alloy.

The fixed layer 23 and the free layer 25 are made of a NiFe alloy,
It is formed with a single-layer structure made of any one of ferromagnetism of a Co alloy, a CoFe alloy, and a CoNiFe alloy, or a multilayer structure of the above ferromagnetic films. As the multilayer structure of the ferromagnetic film, a plurality of layers, for example, two or three layers can be used. Examples of the multilayer structure of the ferromagnetic film are, for example, CoFe / NiFe, or
CoFe / NiFe / CoFe and the like. Further, as the multilayer structure of the ferromagnetic film, a laminated structure of a ferromagnetic film and a non-magnetic layer can be used. Examples of the laminated structure of the ferromagnetic film and the nonmagnetic layer include Co / Ru / Co, CoFe / Ru / CoFe, and the like. These multilayer structures of the ferromagnetic films are effective for preventing diffusion at the interface and suppressing anisotropic dispersion. The thickness of the base film 21 is approximately 3 nm to 10 nm, and the thickness of the antiferromagnetic film 22 is approximately 2 nm to 2 nm.
5 nm, the fixed layer 23 and the free layer 25 are approximately 1 nm to 10 nm.
nm.

Examples of the tunnel barrier layer 24 include various insulating materials.
Layers, for example, oxide or nitride layers, these materials
A laminated film of the material can be used. Tunnel barrier layer 2
In the example of No. 4, for example, Al—O, Si—O, Ta
-O or a single layer film or a laminated film of these materials
Laminated structure sandwiching a conductive film. This stack
A specific example of the structure is, for example, Al-O / Co / Al-O.
You. These oxides may be formed directly.
And oxidize in an oxygen atmosphere or by plasma
Is also good. For example, one example is a metal film, for example, an Al film.
It is formed and oxidized. The thickness of the tunnel barrier layer 24 is
It is extremely thin, approximately 0.5 nm to 3.0 nm. Magnetic flux guide 1
4 indicates that the current flowing from the upper gap film 16 is the lower gap.
This is a region where leakage to the film 12 is prevented. Magnetic flux guy
If a material suitable for the material 14 is used, a high-resistance soft magnetic film,
For example, a multilayer structure of ferromagnetic material and insulating material can be given.
come. To give an example of a multilayer structure of ferromagnetic material and insulating material,
CoFe / Al_TwoO_Three/ CoFe or CoFe / SiO_Two/ CoFe etc.
I can give it. The thickness of the magnetic flux guide 14 is approximately 5 n
m to 15 nm. Examples of the high-resistance soft magnetic film
If MnZnFe _TwoO_Three, NiZnFe_TwoO_Three, FeSi
O, CoAlO and the like. Furthermore, these laminated films
Can be used.

Similarly to the magnetic flux guide 14, the magnetic domain control film 15 is a region for preventing a current flowing from the upper gap 16 from leaking to the lower gap film 12. If a material suitable for the magnetic flux guide 14 is used, a material having a high resistance, for example, Fe ₂ O ₃ , Fe ₃ O ₄ , NiO, or CoO can be used.
The film thickness of the magnetic flux guide 14 is approximately 10 nm to 30 nm.

Next, a method of manufacturing the magnetoresistive sensor 20 will be described.

First, after a lower magnetic shield film 11 is formed on a substrate 10 by a sputtering method or a plating method, a lower gap film 12 is formed by a sputtering method. After ion cleaning the surface of the lower gap film 12, the base film 21 of the TMR film 13 is formed by sputtering.
Antiferromagnetic film 22, pinned layer 23, and tunnel barrier layer 14
Are successively formed in order. After that, the tunnel barrier layer 24 is formed by natural oxidation for several tens minutes in an oxygen atmosphere of several tens Torr without breaking vacuum. further,
The free layer 25 is formed on this upper part. Thus, the TMR film 13 according to the present invention is formed.

After that, a resist film is formed in a desired shape on the TMR film, and then a TM film is formed by ion milling.
The R film 13 is processed into a predetermined shape. After lightly ion-cleaning the surface of the TMR film 13, the flux guide 14 is formed by a sputtering method or a plating method without removing the resist, and the resist is removed. By this step, that is, a so-called lift-off method, a film for the TMR film 13 and the magnetic flux guide 14 having a desired shape is formed. Further TMR
A resist is formed in a predetermined shape on the film 13 and the magnetic flux guide 14, and the magnetic domain control film 15 is processed by a sputtering method.
Lift off the resist. The upper gap film 16 is formed by a sputtering method or an evaporation method. Finally, the upper magnetic shield film 17 is formed by a sputtering method or a plating method to complete the magnetoresistive sensor 20 as shown in FIG.

Further, in this embodiment, the TMR film 13 is composed of a base film 21, an antiferromagnetic film 22, a first ferromagnetic film (fixed layer) 23, a tunnel barrier layer 24, and a second ferromagnetic film in this order from the bottom. The film (free layer) 25 is laminated. However, this TMR
The film can be stacked from the lower side opposite to the second ferromagnetic layer (free layer) 25, tunnel barrier layer 24, first ferromagnetic layer (fixed layer) 23, and antiferromagnetic layer 22. . However, in this case, the underlayer 21 is formed for the purpose of improving the magnetic characteristics of the free layer 25. Also, since the magnetic flux guide 14 must be adjacent to the free layer 25, the TMR film 13
Formed underneath.

Using the magnetoresistive sensor 20 described above, a read head was manufactured, and read characteristics were measured. As a result, good and stable reproduction output was obtained, and noise such as Barkhausen noise and waveform distortion such as baseline shift were not observed. Note that the vertical asymmetry of the reproduced signal was about ± 5%, which was a level that would not cause a problem in practical use.

Embodiment 2 FIGS. 3A and 3B are sectional views of a magnetoresistive sensor 30 according to a second embodiment. 3A is a cross-sectional view parallel to the element height direction 102, and FIG.
1 shows a sectional view parallel to 1. These cross-sectional views are the same as those in FIG. 1 showing how to cut the cross section of the magnetoresistive sensor. 3A and 3B, the same layers and films as those in FIGS. 2A and 2B are denoted by the same reference numerals.

The magnetoresistive sensor 3 shown in FIGS. 3A and 3B
2 differs from the magnetoresistive sensor 20 of FIGS. 2A and 2B in that an insulating film 31 is formed on the upper and / or lower sides of the magnetic flux guide 14. Therefore, in the following description, only different points will be described, and description of other members will be omitted. Other structures, material selection, and the like are sufficient to be configured in the same manner as described in the first embodiment.

In such a structure, it is possible to prevent a current from leaking from the upper gap film 16 to the lower gap film 12 through the magnetic flux guide 14. For this reason, in the present embodiment, the magnetic flux guide 14 does not necessarily need to be formed of a high-resistance material. Therefore, as the magnetic flux guide 14, a metal or alloy material such as a NiFe alloy, a CoNiFe alloy, or a FeSiAl alloy can be used. Suitable materials for the insulating film 31 include Al ₂ O ₃ , SiO ₂ , and a mixture of Al ₂ O ₃ and SiO ₂ . The thickness of the insulating film 31 needs to be at least 10 nm or more in consideration of withstand voltage. Third Embodiment FIGS. 4A and 4B are cross-sectional views of a magnetoresistive sensor 30 according to a second embodiment. FIG. 4A is a cross-sectional view parallel to the element height direction 102, and FIG.
1 shows a sectional view parallel to 1. These cross-sectional views are the same as those in FIG. 1 showing how to cut the cross section of the magnetoresistive sensor. 4A and 4B, the same symbols are given to the same layers and films as in FIGS. 2A and 2B.

The magnetoresistive sensor 3 shown in FIGS. 4A and 4B
2 differs from the magnetoresistive sensor 20 of FIG. 2 in that an insulating film 33 is formed above and / or below the magnetic domain control film 15. Therefore, in the following description,
Only different points will be described, and description of other members will be omitted. Other structures, material selection, and the like are sufficient to be configured in the same manner as described in the first embodiment.

In such a structure, it is possible to prevent a current from leaking from the upper gap film 16 to the lower gap film 12 through the magnetic domain control film 15. Therefore, in this example, the magnetic domain control film 15 does not necessarily need to be formed of a high-resistance material. As a material of the magnetic domain control film 15, Mn
An antiferromagnetic material such as Ir, MnPt, FeMn, CrMn-based alloy, MnPtPd, NiMn-based alloy, or a hard magnetic material such as CoCrPt alloy can be used. In this case, a base film 34 may be formed below the magnetic domain control film 15 in order to increase the coupling magnetic field and the coercive force. Ta, Nb, R
u, Hf, NiFe, Cr and their laminated structure, such as Ta / NiF
Use e. The material of the insulating film 33 is Al ₂ O ₃ , SiO ₂ , or
A mixture of Al ₂ O ₃ and SiO ₂ is a suitable material. The film thickness of the base film 34 is required to be 2 nm to 10 nm, and the film thickness of the insulating film 33 is required to be at least 10 nm in consideration of withstand voltage.

Fourth Embodiment FIGS. 5A and 5B are cross-sectional views of a magnetoresistive sensor 35 according to a fourth embodiment. 5A is a sectional view parallel to the element height direction, and FIG. 5B is a sectional view parallel to the track width direction. These cross-sectional views are the same as those in FIG. 1 showing how to cut the cross section of the magnetoresistive sensor. FIG. 5A
5B, the same symbols are given to the same layers and films as in FIGS. 2A and 2B.

The magnetoresistive sensor 3 shown in FIGS. 5A and 5B
5 is different from the magnetoresistive sensor 20 shown in FIG. 2 in that the magnetic flux guide 14 extends continuously from the medium surface of the TMR film 13 to the opposite surface, and the free layer 26 of the TMR film 13 and the magnetic flux guide 14 That is, the intermediate layer 36 is formed therebetween. In this case, the magnetic flux guide 14 and the free layer 26 are
6, ferromagnetically or diamagnetically coupled. In this example, the intermediate layer 36 has a thickness of 0.5 nm to 1 nm.
Of Ru was used.

Accordingly, in the following description, only different points will be described, and description of other members will be omitted. Other structures, material selection, and the like are sufficient to be configured in the same manner as described in the first embodiment.

Embodiment 5 FIGS. 6A and 6B are cross-sectional views of a magnetoresistive sensor 37 according to a fourth embodiment. 6A is a sectional view parallel to the element height direction, and FIG. 6B is a sectional view parallel to the track width direction. These cross-sectional views are the same as those in FIG. 1 showing how to cut the cross section of the magnetoresistive sensor. FIG. 6A
6B, the same symbols are given to the same layers and films as in FIGS. 2A and 2B.

In the magnetoresistive sensor 37 shown in FIGS. 6A and 6B, the magnetic flux guide 14 is provided above the magnetic domain control film 15.
Are laminated. The TMR film 13 is formed so as to extend continuously from the medium surface of the TMR film 13 to the opposing surface. Here, the magnetic flux guide 14 may be formed directly on the magnetic domain control film 15 or may be formed via a first intermediate layer 38 for adjusting the coupling.

It is also possible to form a second intermediate layer 36 between the free layer 26 of the TMR film 13 and the magnetic flux guide 14. In this case, the magnetic flux guide 14 and the free layer 26 are magnetically coupled via the intermediate layer 36. In this configuration, the magnetic domain control film 15 controls the magnetic domains of the magnetic flux guide 14, so that the magnetic domains of the free layer 26 can be controlled at the same time.

Sixth Embodiment FIG. 8 is a perspective view of a magnetoresistive sensor according to a sixth embodiment.

On a substrate 40, a base film 41, a protective film 42,
MR film 43, first magnetic flux guide 44, magnetic domain control film 45,
An insulating gap film 48 and a second magnetic flux guide 49 are formed. The base film 41 and the second magnetic flux guide 49 each have an extraction electrode terminal portion 50. The lead electrode terminal portion 50 also serves as an electrode for flowing a current in the thickness direction of the TMR film 43.

When the azimuth of the magnetoresistive sensor is defined as a track width direction 101, an element height direction 102, and a magnetic head driving direction 103, A and B in FIG.
The cross section parallel to the element height direction 102 and the track width direction 101 is shown.

FIG. 9A is a sectional view parallel to the element height direction 102 of the magnetoresistive sensor 39, and FIG. 9B is a sectional view parallel to the track width direction 101.

In this example, a base film 41 is formed on a substrate 40 in a predetermined shape. On the base film 41, a TMR film 43 is disposed at a position away from the air bearing surface. In this example, the protective film 42 is formed so as not to run over the end of the TMR film 43. The configuration of the TMR film 43 is the same as that of the TMR film 13 shown in FIG.

Further, a first intermediate layer 46, a first magnetic flux guide 44, a second intermediate layer 47, and a magnetic domain control film 45 are sequentially formed from the bottom, and the element height is set above the TMR film 43 from the air bearing surface side. They are arranged so as to extend continuously in the direction 102. First
The magnetic flux guide 44 is a soft magnetic film that guides the magnetic flux from the medium to the TMR film 43.
It is magnetically coupled to the R film 43. The magnetic domain control film 45
The ferromagnetic film is a ferromagnetic film to which a bias magnetic field is applied in order to suppress the generation of magnetic domains in the magnetic flux guide 14 and the free layer 25 of the TMR film. T
On the MR film 43, the magnetic flux guide 44, and the magnetic domain control film 45, an insulating gap film 48 is arranged so as to surround them. Further, a second magnetic flux guide 49 is disposed on the insulating gap film 48. The first magnetic flux guide 44 and the second magnetic flux guide 49 are in contact with each other on the side 51 opposite to the air bearing surface. The second magnetic flux guide 49 and the underlying film 41 each have a lead electrode terminal portion 50, and the application of electric current and the detection of the reproduction output are performed by connecting the electric terminals. When a current flows through these electrode terminal portions 50, the first magnetic flux guide 44 passes through the connecting portion 51 from the second magnetic flux guide 49,
It flows in the thickness direction of the TMR film 43.

Next, various materials will be described.

The surface of the under film 41 is desirably smooth and clean so that the characteristics of the TMR film 43 are stable and the resistance change amount is high, and the under film 41 and the lower gap film 12 of the first embodiment (FIG. 2) are used. It is formed of the same kind of material. This base film 41
Has a thickness of 3 to 30 nm.

Since the first and second magnetic flux guides 44 and 49 also serve as electrodes, they are formed of a low-resistance soft magnetic film, for example, a NiFe alloy, a CoNiFe alloy, or a FeSiAl alloy. The film thickness is 5
20 nm. Protective film 42 and insulating gap film 48
Is formed of Al ₂ O ₃ , SiO ₂ , and Al ₂ O ₃ .SiO ₂ . The film thickness needs to be at least 20 nm in consideration of the withstand voltage. Other first and second intermediate layers 46 and 47, magnetic domain control film 4
5. The TMR film 43 is formed of the same material as that described in the first to fifth embodiments.

In this embodiment, the base film 41,
Although the TMR film 43, the first magnetic flux guide 44, the insulating gap film 46, and the second magnetic flux guide are stacked, they can be stacked in reverse order. Further, in the present embodiment, the electrode terminal portion 50 is disposed on the second magnetic flux guide 49, but may be provided on the first magnetic flux guide 44. Furthermore, in the magnetoresistive sensor formed by the first and second two magnetic flux guides as in the present embodiment, both the first and second magnetic flux guides may be subjected to magnetic domain control.

In this embodiment, the magnetic domain control film 45 and the magnetic flux guide 44 are stacked. However, the structures shown in the first to fourth embodiments can be applied to the sixth embodiment.

Using the magnetoresistive sensor 39, a read head was manufactured, and read characteristics were measured. As a result, good and stable reproduction output was obtained, and noise such as Barkhausen noise and waveform distortion such as baseline shift were not observed. Note that the vertical asymmetry of the reproduced signal was about 5%, which was a level that would not cause a problem in practical use.

Embodiment 7 FIG. 7 schematically shows a magnetic disk drive provided with a magnetoresistive sensor 20 to which the present invention is applied. A recording medium made of a CoCrPt-based alloy film is deposited on the surface of a magnetic disk 53 such as a metal or glass disk rotated at a high speed by a spindle motor 54, for example, by a sputtering method. In this apparatus, a ceramic chip (slider) 55 that floats by receiving an air flow accompanying the rotation of the disk
Digital signals can be recorded / reproduced on a recording medium using the thin film magnetic head formed thereon. Examples of the thin-film magnetic head include an inductive recording head including a NiFe-based alloy magnetic pole and a Cu coil, and a yoke-type magnetic head described in the first embodiment.

Further, the ceramic chip is mounted on a movable arm, and the arm can be moved substantially in the radial direction by an actuator 56 having a voice coil motor. Therefore, the thin film magnetic head can access almost the entire surface of the disk. In addition to the recording signal, there is a servo signal for designating a track position on the recording medium, and the servo signal reproduced by the reproducing head is fed back to the actuator so that the positioning of the head can be performed with high accuracy by closed loop control. . Further, a data signal recording / reproducing system 57 and an electric circuit system 58 for processing a reproducing signal and a servo signal and controlling a mechanical system are also provided. In this apparatus, a high recording density could be achieved by using the thin film magnetic head disclosed above. As a result, a small-sized and large-capacity device could be realized.

Although the apparatus having one disk is disclosed here, it is apparent that the same effect can be obtained with an apparatus having a plurality of disks.

[0084]

According to the present invention, in a yoke type magnetoresistive sensor using a tunnel magnetoresistive film, a Barkhausen noise can be suppressed and a stable magnetoresistive sensor can be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view of a magnetoresistive sensor according to a first example of the present invention.

FIG. 2A is a sectional view in the height direction of the magnetoresistive sensor according to the first embodiment of the present invention, and FIG. 2B is a cross section in the track width direction of the magnetoresistive sensor according to the first embodiment of the present invention; FIG.

FIG. 3A is a sectional view in the height direction of a magnetoresistive sensor according to a second example of the present invention, and FIG.
FIG. 4 is a cross-sectional view in the track width direction of the magnetoresistive sensor according to the example of FIG.

FIG. 4A is a sectional view in the height direction of a magnetoresistive effect sensor according to a third example of the present invention, and FIG. 4B is a third example of the present invention.
FIG. 4 is a cross-sectional view in the track width direction of the magnetoresistive sensor according to the example of FIG.

FIG. 5A is a sectional view in the height direction of a magnetoresistive sensor according to a fourth example of the present invention, and FIG.
FIG. 4 is a cross-sectional view in the track width direction of the magnetoresistive sensor according to the example of FIG.

FIG. 6A is a sectional view in the height direction of a magnetoresistive sensor according to a fourth example of the present invention, and FIG.
FIG. 4 is a cross-sectional view in the track width direction of the magnetoresistive sensor according to the example of FIG.

FIG. 7 is a diagram illustrating a configuration of a magnetic recording / reproducing apparatus according to the present invention.

FIG. 8 is a perspective view of another example of a magnetoresistive sensor according to the present invention.

9A is a sectional view in the height direction of another example of a magnetoresistive sensor according to the present invention, and FIG. 9B is a sectional view in the track width direction of another example of the magnetoresistive sensor according to the present invention. FIG.

FIG. 10 is a perspective view showing a configuration of a magnetic recording / reproducing apparatus according to the present invention.

FIG. 11 is a plan view of a magnetoresistive sensor according to a first example of the present invention.

FIG. 12 is a cross-sectional view showing various examples of the arrangement of a magnetic flux guide and a magnetic domain control layer.

FIG. 13 is a cross-sectional view illustrating the outline of magnetic domain control of TMR.

[Explanation of symbols]

13, 43 ... tunnel magnetoresistive film, 25 ... ferromagnetic film (free layer), 24 ... tunnel barrier layer, 23 ... ferromagnetic film (fixed layer), 22 ... antiferromagnetic film, 21, 34,
42 underlayer film, 10, 40 substrate, 11 lower magnetic shield film, 12 lower gap film, 14, 44,
49 magnetic flux guide, 15, 45 magnetic domain control film, 16
..Upper gap film, 17 ... Upper magnetic shield film, 1
8, 50 · · · electrode terminal part, 19 · · · through hole, 31, 33
..Insulating film, 36, 38, 46, 47..Intermediate layer, 48
..Insulating gap film, 42..Protecting film, 20, 30, 3
2, 35, 37, 39 ··· Magnetoresistance sensor, 52 ·
.Magnetic recording and reproducing devices, 53..Magnetic disks, 54 ..
Spindle motor, 55 slider, 56 actuator, 57 signal processing circuit.

Claims (7)

[Claims] 1. The method according to claim 1, wherein the magnitude of the applied external magnetic field is varied.
Film having a magnetic layer whose magnetization direction changes
And a magnetic flux guide for guiding an external magnetic field to the magnetic layer.
The magnetic flux guide comprises a CoFe alloy film and Al_TwoO_ThreeMulti with membrane
Layer structure or CoFe alloy film and SiO _TwoBecause of the multilayer structure with the membrane
A magnetic head characterized in that: 2. A magnetoresistive film having a magnetic layer whose magnetization direction changes according to the magnitude of an applied external magnetic field, and a magnetic flux guide for guiding an external magnetic field to the magnetic layer, Magnetic flux guide is MnZnFe ₂ O ₃ film, NiZnFe ₂ O ₃ film,
A magnetic head comprising at least one of a FeSiO film and a CoAlO film. 3. A magnetoresistive film having a magnetic layer whose magnetization direction changes according to the magnitude of an applied external magnetic field, and a magnetic flux guide for guiding an external magnetic field to the magnetic layer, A magnetic head, wherein the magnetic flux guide has a multilayer structure of a ferromagnetic film and an insulating film. 4. The magnetic head according to claim 1, wherein the magnetic flux guide has a higher electric resistance than the magnetoresistive film. 5. A magnetoresistive film having a magnetic layer whose magnetization direction changes in accordance with the magnitude of an applied external magnetic field, and magnetically coupled to said magnetic layer via an intermediate layer. A first magnetic flux guide for guiding an external magnetic field to the layer, and the first magnetic flux guide is formed via a non-magnetic gap layer, and is connected to the first magnetic flux guide at an end opposite to the air bearing surface. A second magnetic flux guide, wherein the first magnetic flux guide and the second magnetic flux guide are made of a NiFe alloy film, a Co NiFe alloy film, or a FeSiAl alloy film. 6. The magnetic head according to claim 5, wherein an electrode terminal is connected to at least one of the first magnetic flux guide and the second magnetic flux guide. 7. A free layer whose magnetization direction changes in accordance with the magnitude of an applied external magnetic field, and a fixed layer whose magnetization direction is fixed with respect to an applied external magnetic field. 2. The layer according to claim 1, wherein the layer is a tunnel-type magnetoresistive film formed via a tunnel barrier layer.
7. The magnetic head according to any one of items 6 to 6.