JP2003077107A - Magneto-resistance effect type magnetic head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the detection sensitivity of a spin valve type magnetic head. SOLUTION: In a constitution where the spin valve type magnet-resistance effect element of a CPP (Current Perpend: cular to Plane) is arranged to be retreated from an ABS surface 16, and a part or all parts of a magnetization free layer in the spin valve element layer are exposed to the ABS surface 16 to also serve as magnetic flux guide layers, a laminated Fery structure is employed where the magnetization freely layer is divided by a nonmagnetic layer 22, first and second magnetization free layers 21 and 23 are set to be different in film thickness × magnetization amount and, by setting the film thickness × magnetization amount of the first magnetization free layer smaller than the film thickness ×magnetization amount of the second magnetization free layer 23, detection sensitivity is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called spin-valve type giant magnetoresistive effect (GMR effect) or tunnel magnetoresistive effect magnetic head, which is particularly applied to hard disk drive devices and the like.

[0002]

2. Description of the Related Art A magnetic head having a magnetoresistive effect element as a magnetic sensitive section is widely used as a converter capable of reproducing a magnetic signal recorded at a high recording density and reading a recording signal magnetic field from a magnetic recording medium. It is commonly used. Conventionally, a general magnetoresistive effect element has an anisotropic magnetoresistive effect in which its resistance changes in proportion to the square of the cosine of the angle formed by the magnetization direction of the element and the conduction direction of a sense current flowing in the element. Is used.

On the other hand, recently, a resistance change of a device in which a sense current is flowing occurs due to spin dependence of conduction electrons between magnetic layers via a nonmagnetic layer and spin dependence scattering at a different layer interface. There is a trend toward the use of magnetic heads using the GMR effect and, above all, the magnetoresistive effect of the spin valve GMR. The structure of the spin valve type GMR is
One of the pair of ferromagnetic layers arranged via the non-magnetic intermediate layer is used as a fixed magnetization layer by fixing the magnetization by exchange coupling with the antiferromagnetic layer, and the other ferromagnetic layer is perpendicular to the fixed layer. The magnetization free layer is set so that it is biased weakly so that the magnetization direction is maintained and the magnetization is sensitively rotated by the leakage signal magnetic field from the magnetic recording medium. A change in the degree of scattering of the flowing electrons depending on the relative angle between the magnetization of the fixed layer and the magnetization of the free layer changes the electric resistance, and a signal can be read. Magnetoresistive element using the magnetoresistive effect due to this spin valve effect (hereinafter referred to as SV type GMR element)
Is applied to magnetic sensors and magnetic heads that have a larger resistance change than the anisotropic magnetoresistive effect and have high sensitivity.

By the way, when the recording density of the magnetic recording medium is up to about 50 Gb / inch 2, the so-called CIP in which the sense current is in the in-plane direction of the thin film.
Although a (Current In-Plane) configuration can be adopted, the recording density is further increased to, for example, 100 G.
When b / inch2 or more is required, the track width is required to be about 0.1 μm or less. In this case, even if the latest dry process is used as the patterning technique in the current device fabrication, the CIP structure is used. Finally, it was necessary to polish the magnetoresistive effect element height on the ABS surface by machining, and the accuracy of the element size was also limited. Further, there has been a problem that the resistance change rate of the magnetoresistive effect in the CIP structure is insufficient.

On the other hand, in the SV type GMR element,
CPP for passing a detection current in a direction perpendicular to the film surface
(Current Peripheral To
There has been proposed a GMR element having a the plane (current flowing in a plane) configuration. As a CPP type GMR element, a TMR element utilizing a tunnel current has been studied, and recently, a spin valve type element or a multilayer film type element has been studied (for example, Japanese Patent Publication No. 11-5099).
56, JP-A-2000-228004, JP-A-2000
228004, Proc. Of the 24th Japan Society for Applied Magnetics 2000, p. 427).

[0006]

As described above, with the improvement of the magnetic recording density, the reading sensor sandwiched between the soft magnetic lower layer shield 6 and the upper layer shield 7 as shown in FIG. In order for the shield type magnetic sensor to have a narrower gap, the spin valve GMR which becomes the reading sensor 1 in the conventional structure in which the sensor portion spin valve GMR film or TMR film is exposed to the ABS surface.
Alternatively, thinning the TMR element is an essential condition for increasing the sensitivity. That is, it is necessary to make the film thickness of the spin valve element equal to or smaller than the gap length of the sensor. Furthermore, when the gap length between the shields is narrowed (for example, when the gap length is 200 Gbpsi class: gap length is 60 nm or less), the magnetic field sensitive portion should be centered between the magnetic shields due to the limitation of thinning the material. With the conventional structure of FIG.

In the magnetic sensor that also functions as a magnetic flux guide, since only the magnetic flux guide 12 is exposed to the ABS surface, it is easy to deal with the narrowing of the magnetic sensor gap. For example, as shown in FIG. 2B, the spin valve GMR or TMR element portion 13 which is the reading sensor portion can be provided at a position separated from the ABS surface 16 by the magnetic flux guide length. The film thickness of the magnetic flux guide and the insulating property between the magnetic flux guide 12 and the magnetic shield are only limited, and the film thickness of the spin valve GMR or TMR can be freely set. GMR or T by this magnetic flux guide 12
When the magnetic flux is introduced into the MR film magnetic sensing section 14 (element magnetic sensing section),
The magnetic flux penetration length λ is determined by the magnetic flux guide thickness, the magnetic shield gap length, and the magnetic flux guide layer magnetic permeability. For example, when the gap length is 60 nm, as shown in FIG. The amount of magnetic flux introduced into the magnetic part increases. Therefore, in order to increase the element detection sensitivity with the same magnetic flux guide length, it is desirable that the magnetic flux guide thickness be thick.

On the other hand, the amount of resistance change that is the sensor output is
It is proportional to the amount of magnetization rotation of the element magnetic sensitive section 14 of the sensor. The amount of magnetization rotation is determined by the ratio of the amount of magnetic flux flowing from the magnetic flux guide 12 to the amount of magnetization of the element magnetic sensing unit 14, and the smaller the amount of magnetization of the element magnetic sensing unit 14, the greater the amount of magnetization rotation. Can be greatly increased. Therefore, it is desirable that the magnetic flux guide thickness be thick and the element magnetic sensitive layer thickness be thin. However, the magnetic flux guide 12 and the element magnetic sensitive section 14
4 is formed as a continuous film in the manufacturing process order shown in FIG. 4, a GMR having a laminated structure is formed.
The film thickness or the film thickness of the element magnetic sensitive portion 14 of the TMR film 13 is such that the magnetic flux guide layer thickness ≦ the element magnetic sensitive portion layer thickness, and the combination thereof is limited. Therefore, the magnetic flux is maintained while maintaining the element detection sensitivity. It was impossible to improve the magnetic flux transmission efficiency of the guide 12.

[0009]

The present invention is directed to a CPP type spin valve magnetoresistive effect element, and a pair of magnetic shield layers 6 and 7 arranged so as to sandwich the spin valve element layer.
In a configuration in which the spin valve element layer is arranged so as to recede from the ABS surface 16 and part or all of the magnetization free layer in the spin valve layer is exposed to the ABS surface 16 so as to also serve as the magnetic flux guide layer 12, 5, the magnetization free layer 2
The first magnetization free layer 21 has a laminated ferri structure in which reference numerals 1 and 23 are divided by the nonmagnetic layer 22 and are antiferromagnetically coupled to each other.
And the thickness of the second magnetization free layer 23 × the amount of magnetization are different, and the thickness of the first magnetization free layer 21 × the amount of magnetization is the thickness of the second magnetization free layer 23 × the magnetization. It is proposed to be smaller than the quantity.

Further, the magnetization free layer has a laminated ferri structure divided by non-magnetic layers, and a part of the film thickness of the first magnetization free layer 21 facing the magnetization fixed layer 19 side in the spin valve element layer. Is exposed on the ABS surface as a layer also serving as a magnetic flux guide, or the entire thickness of the first magnetization free layer 21 is AB.
All of the film thickness of the second magnetization free layer 23 or a part of the film thickness of the second magnetization free layer 23 is exposed from the ABS 16 as a layer which also serves as a magnetic flux guide. In the structure of the spin valve element layer, a top spin valve structure in which the magnetization free layer is arranged on the substrate side or a bottom pin valve structure in which the magnetization fixed layer is arranged on the substrate side can be adopted.

Further, as shown in FIG. 9, the above-mentioned magnetization pinned layer has a second magnetization pinned layer 19- sandwiching a first magnetization pinned layer 19-1 adjacent to the antiferromagnetic layer and a non-magnetic conductive layer 24. By adopting a laminated ferri structure composed of 2 and antiferromagnetically coupled to each other, the static magnetic field acting on the magnetization free layer from the magnetization fixed layer is reduced, and the sensitivity becomes high and the laminated ferri structure becomes sensitive. It is also possible to control the asymmetry of the reproduced waveform with respect to the magnetization free layer.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Examples of the present invention will be described, but the scope of the present invention is not limited thereto. In the element patterning process shown in FIG. 4, the magnetic flux guide layers and the magnetic sensing layers 12 and 14 are formed of non-magnetic layers 22 such as Ru and R.
A CPP spin-valve type GMR constructed by introducing a laminated ferrimagnetic free layer composed of a first magnetic free layer 21 and a second magnetic free layer 23 separated by h, Ir (thickness 2 to 20Å) or the like, or Configure TMR. Here, the respective ferromagnetic layers forming the first magnetization free layer 21 and the second magnetization free layer 23, such as NiFe, CoFe, Co, and NiF, are used.
The thickness of the nonmagnetic layer is adjusted so that eCo or the like has an antiferromagnetically coupled state via the nonmagnetic layer. That is, the magnetization moments of the first magnetization free layer 21 and the second magnetization free layer 23 are oriented in antiparallel directions, and the mutual magnetization Ms × thickness t.
Difference contributes to effective magnetic rotation.

CP having this laminated ferrimagnetic free layer
A P spin valve type GMR or TMR is constructed. That is, in the case of GMR, the non-magnetic intermediate layer 20 is, for example, C
A conductive layer such as u was formed to a thickness of 2 nm, for example. In the case of TMR, the non-magnetic intermediate layer 20 is an insulating layer such as Al2O3 and has a thickness of 0.8 n, for example.
The film was formed as m. The first magnetization free layer 21 in FIG.
By setting the film thickness of the second magnetization free layer 23 and setting the etching depth of the magnetic sensitive layer 14 at an arbitrary position in the etching step of FIG. 4B, the effective magnetic flux guide layer thickness Then, the effective magnetic sensing part layer thickness can be determined.
That is, as shown in FIG. 5, the first magnetization free layer thickness and the second magnetization free layer thickness during the etching of FIG.
When 0 <t1 ′ ≦ t1, when t1 ′ = 0, t
The case where 1 ′ = 0 and 0 <t2 ′ ≦ t2 can be arbitrarily selected.

At this time, the effective magnetic flux guide layer and the magnetic sensitive layer can be variably selected as follows: (layer thickness × magnetization amount) as shown in FIGS. 5 (a) (b) (c). Figure 5 (a)
Then, effective magnetic flux guide thickness x magnetization amount = t2 x M2-t1 '
X M1, effective magnetic sensing layer thickness x amount of magnetization = t2 x M2-t1 x
It becomes M1. In FIG. 5B, effective magnetic flux guide thickness × magnetization amount = t2 × M2, effective magnetic sensing part layer thickness × magnetization amount = t2 × M2
−t1 × M1. In FIG. 5C, effective magnetic flux guide thickness × magnetization amount = t2 ′ × M2, effective magnetic sensing part layer thickness × magnetization amount =
It becomes t2 * M2-t1 * M1. With the configuration of the present invention, it is possible to effectively satisfy the condition of magnetic flux guide layer thickness> element magnetic sensitive layer thickness by setting the above t1, t1 ′, t2, t2 ′, M1, M2, etc. A reading sensor having the magnetic flux guide layer thickness and the element magnetic sensitive portion thickness can be obtained.

FIG. 6A shows a cross section (a) -1 in the depth direction of the reading element section and a cross section (a) -2 parallel to the film surface as the present embodiment. FIG. 6B shows a cross section (b) -1 in the depth direction of the reading element portion and a cross section (b) -2 parallel to the film surface as a comparative example. Note that the thicknesses of the first magnetization free layer 21 and the second magnetization free layer 23 are t1 × M1 <t2 because the magnetization state changes depending on the size relationship as shown in FIGS. 6A and 6B. The point of the present invention is to make xM2. That is, similarly to the patterning of the magnetic flux guide, a stabilizing permanent magnet film for stabilizing the element operation is provided on the element having the track width patterning, and t1 × M1 <t2 with respect to the magnetic field from the magnet film.
In the case of × M2, the magnetization in the plane of the second magnetization free layer is
The magnetic flux guide portion 12 and the second magnetization free layer 23 are shown in FIG.
As shown in (a) -2, the magnetic domains do not occur because they are oriented in the same direction, but when t1 × M1> t2 × M2, in the second magnetization free layer, as shown in FIG. 6B, It can be seen that a 180 degree domain wall is generated at the boundary with the magnetic flux guide section 12 and the magnetic domain exists, so that it is difficult to stabilize the operation and it is not suitable.

FIG. 7A shows a top type spin valve TSV on the fixed layer used in the above description: FIG.
(B) is a bottom type spin valve under the fixed layer:
An example of arrangement of BSVs is shown. FIG. 7 shows both (a) and (b) as an example of a configuration in which only the second magnetization free layer also serves as a magnetic flux guide. In the BSV type of FIG. 7B, the selection of the effective magnetic flux guide layer thickness and the magnetic sensitive layer thickness cannot be changed by etching, but the first free layer t1, M
When the first and second free layers t2 and M2 are used, the magnetic flux guide thickness:
The present invention can be implemented by selecting the effective film thickness of t2 × M2 and the magnetic sensitive portion: t2 × M2-t1 × M1.

FIGS. 8A and 8B show an example of a cross section perpendicular to the depth direction of the magnetoresistive effect element when the stabilizing permanent magnet film 3 is provided at the time of forming the element track width to stabilize the element. . FIG. 8A shows a top spin valve type configuration, FIG. 8A-1 is a cross-sectional configuration parallel to the ABS plane in the element magnetic sensing part, and FIG. 8A-2 is an ABS configuration. It is the structure of the surface. FIG. 8B shows a bottom spin valve type structure, FIG. 8B-1 is a cross-sectional structure parallel to the ABS surface in the element magnetic sensing part, and FIG. 8B-2 is
This is the ABS structure. In the above structure, in order to prevent current leakage between the upper and lower electrodes, a permanent magnetic film laminated with an insulating film applies a bias magnetic field from the element stabilizing permanent magnet to both free layers. The arrow of the stabilizing permanent magnet film 3 is in the magnetization direction, and biases the magnetization free layer in the direction orthogonal to the magnetization fixed layer.

Further, as shown in FIG. 9, the magnetization pinned layer is a first magnetization pinned layer 19-1 adjacent to the antiferromagnetic layer.
(Eg CoFe) and non-magnetic conductive layer 24 (eg Ru)
The second magnetization fixed layer 19-2 (for example, CoFe) sandwiching
And the magnetization amount of the two ferromagnetic films is M
When s × film thickness t is different, the net M of the laminated film as a whole
s × t can be expressed as the difference between both Ms × t.
By using the magnetization pinned layer of this laminated ferri, the static magnetic field acting on the magnetization free layer from the magnetization pinned layer is reduced, and the asymmetry of the reproduced waveform with respect to the magnetization free layer of the laminated ferri structure becomes sensitive and becomes sensitive. It can also be controlled.

[0019]

As described above, according to the present invention, the magnetic flux guide thickness <the spin valve element thickness to narrow the gap and the magnetic flux guide thickness> the effective magnetization free layer thickness, corresponding to the high density magnetic recording, Further, by reducing the effective magnetization amount × film thickness of the magnetization free layer, high sensitivity and high stability (no magnetic domain is generated) are realized. More specifically, the recording signal wavelength and the signal track width are narrowed by the high-density magnetic recording, and the signal leakage magnetic flux from the recording medium is minimized, while the sensitivity of the magnetoresistive effect element flows from the magnetic flux guide layer. The higher the ratio of the amount of magnetic flux to the magnetic effective thickness of the magnetization free layer, the more advantageous it becomes.
Further, although the magnetic flux penetration length of the magnetic flux guide is proportional to the magnetic permeability of the magnetic flux guide and the gap length of the magnetic shield, it is also related to the film thickness of the magnetic flux guide as shown in FIG. It became possible to satisfy the condition of high sensitivity by making it thicker than the effective thickness of.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view of a magnetic head according to the present invention.

FIG. 2A is a cross-sectional view of a conventional magnetic head in which a magnetoresistive effect element is exposed on an ABS surface. Figure 2
FIG. 3B is a sectional view of a magnetic flux guide type magnetic head according to the present invention.

FIG. 3 is a diagram showing a relationship between a magnetic flux penetration length λ of a magnetic flux guide and a magnetic flux guide thickness.

FIG. 4A to FIG. 4E are cross-sectional views showing a manufacturing process for forming a magnetic flux guide.

5A to 5C are cross-sectional views showing examples in which the thickness of the magnetization free layer of the laminated ferri structure and the thickness of the magnetic flux guide are different.

6 (a) and 6 (b) are cross-sectional views showing the relationship between the film thickness of each of the first magnetization free layer, the second magnetization free layer, and the magnetic flux guide layer and the generation of magnetic domains. .

7A and 7B are cross-sectional views of a top spin valve type and a bottom spin valve type embodiments of the present invention.

8A and 8B are cross-sectional views of an arrangement example of a stabilizing permanent magnet in the present case.

FIG. 9 is a cross-sectional view showing a laminated ferri structure of a magnetization fixed layer in the present case.

[Explanation of symbols]

1 ... Read sensor, 2 ... Substrate, 3 ... Stabilizing permanent magnet film, 4 ... Insulating film, 5 ... Alumina layer,
6 ... Lower shield, 7 ... Middle shield, 8 ...
.Recording magnetic gap, 9 ... Recording magnetic core, 10 ...
・ Thin film coil, 11 ... Electrode layer, 12 ... Flux guide layer, 13 ... Spin valve element, 14 ... Magnetism sensing portion (magnetization free layer), 15 ... Insulating layer, 16 ...・ ABS
Surface, 17 ... Resist, 18 ... Antiferromagnetic layer, 19
... Magnetization pinned layer, 20 ... Non-magnetic conductive intermediate layer or insulating intermediate layer, 21 ... First magnetization free layer, 22 ...
・ Non-magnetic conductive layer (free layer laminated ferri intermediate layer), 23 ・
..Second magnetization free layer 24 ... Non-magnetic conductive layer (fixed layer laminated ferri intermediate layer)

Claims (8)

[Claims] 1. A so-called CP for passing a detection current perpendicularly to a film surface.
P-type (Current Perpendicular)
A spin valve type magnetoresistive effect element (hereinafter referred to as a spin valve element layer) of To the Plane), a pair of magnetic shield layers arranged so as to sandwich the spin valve element layer, and the spin valve element layer on the medium facing side. The so-called A
It is arranged so as to recede from the BS plane (Air Bearing Surface), and AB is so arranged that part or all of the magnetization free layer in the spin valve element layer also functions as a magnetic flux guide layer.
In the structure exposed on the S-plane, the magnetization free layer is a so-called laminated ferri structure divided by a non-magnetic layer, and the first magnetization free layer and the second magnetization free layer have different thicknesses × magnetization amounts. Characteristic magnetoresistive effect magnetic head. 2. A so-called laminated ferri structure in which the magnetization free layer is divided into nonmagnetic layers and antiferromagnetically coupled to each other, and has a first magnetization facing the magnetization fixed layer side in the spin valve element layer. 2. The magnetoresistive effect magnetic head according to claim 1, wherein the film thickness of the free layer × the amount of magnetization is smaller than the film thickness of the second magnetization free layer × the amount of magnetization. 3. A so-called laminated ferri structure in which the magnetization free layer is divided into nonmagnetic layers and antiferromagnetically coupled to each other, and a first magnetization facing the magnetization fixed layer side in the spin valve element layer. Part of the film thickness of the free layer is exposed on the ABS surface as a layer that also serves as a magnetic flux guide, or the entire film thickness of the first magnetization free layer recedes from the ABS surface, and 3. The magnetoresistive effect magnetic head according to claim 1, wherein all or part of the film thickness of the second magnetization free layer is exposed on the ABS surface as a layer also serving as a magnetic flux guide. 4. The spin-valve element layer comprises a magnetic shield layer, a non-magnetic electrode layer, as main constituent layers from the non-magnetic substrate side,
A so-called top-type spin valve structure in which a second magnetization free layer, a nonmagnetic layer, a first magnetization free layer, a nonmagnetic intermediate layer, a magnetization fixed layer, an antiferromagnetic layer, a nonmagnetic electrode layer, and a magnetic shield layer are formed in this order. The magnetoresistive effect magnetic head according to claim 1, 2, or 3. 5. The spin-valve element layer comprises a magnetic shield layer, a non-magnetic electrode layer, and a main constituent layer from the non-magnetic substrate side.
A so-called bottom type pin valve structure in which an antiferromagnetic layer, a magnetization fixed layer, a non-magnetic intermediate layer, a first magnetization free layer, a non-magnetic layer, a second magnetization free layer, a non-magnetic electrode layer, and a magnetic shield layer are formed in this order. The magnetoresistive effect magnetic head according to claim 1, 2, or 3. 6. The so-called laminated ferrimagnetic layer, wherein the magnetization pinned layer is composed of a first magnetization pinned layer, a nonmagnetic conductive layer and a second magnetization pinned layer which are adjacent to the antiferromagnetic layer and which are antiferromagnetically coupled to each other. The magnetoresistive effect magnetic head according to claim 1, 2, 3, 4, or 5, which has a configuration. 7. The non-magnetic intermediate layer is a conductive layer and is a so-called GMR element.
4. The magnetoresistive effect magnetic head described in 4, 5, or 6. 8. The non-magnetic intermediate layer is an insulating layer and is a so-called tunnel MR element.
2. The magnetoresistive effect magnetic head described in 2, 3, 4, 5 or 6.