JPH1187803A - Magnetic resistance effect element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a magnetic resistance change rate and at the same time magnetic sensitivity, by dispersing a projecting part in an island shape for forming a foundation layer, and by laminating ferromagnetic and non-magnetic conductive layers on the foundation layer. SOLUTION: A first foundation layer 2 consisting of Ta is formed on a substrate 1 consisting of Si, and a second foundation layer 3 consisting of Cu is formed on the first foundation layer 2. A projecting part 3a is dispersed in an island shape for forming on the second foundation layer 3, and a foundation layer 10 is constituted of the first and the second foundation layers 2 and 3. Furthermore, CoFe, Cu, CoFe, and IrMn layers that are ferromagnetic, non- magnetic conductive, ferromagnetic, and antiferromagnetic layers 4, 5, 6, and 7, respectively, are successively laminated and a spin valve-type magnetic resistance effect film is formed, thus increasing a magnetic resistance change rate and a one-axis anisotropy magnetic field and improving magnetic sensitivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-resistance effect element, and more particularly to a high-output magneto-resistance effect element using a giant magneto-resistance effect film.

[0002]

2. Description of the Related Art In recent years, as a read-only magnetic head used for a hard disk (HDD), a magnetoresistive (M
R) Heads are attracting attention. The MR head is a head that detects a change in an external magnetic field by a change in electric conductivity, has a higher magnetic field sensitivity than a conventional inductive magnetic head, and can achieve high-density recording. Such MR
As a magnetoresistive material used for the head,
3d transition metal alloy such as permalloy is adopted,
A signal is detected by increasing or decreasing the resistance (anisotropic magnetoresistance effect: AMR) corresponding to the change in the magnetization direction.

However, recently, the giant magnetoresistive effect (GM) showing an order of magnitude higher resistance change than the conventional AMR has
An R) type magnetoresistive material has been found and attracted attention. The GMR material generally has a laminated structure in which a ferromagnetic layer and a nonmagnetic conductive layer are laminated.

As one of such GMR materials, there is a GMR material called an artificial lattice type. This artificial lattice type GMR material is, for example, a magnetoresistive film in which Co layers and Cu layers are alternately laminated to form antiferromagnetic coupling between Co—Co layers. As other GMR materials, coercive force difference type and spin valve type GMR materials are known. The coercive force difference type GMR material has a sandwich structure in which a nonmagnetic conductive layer such as a Cu layer is sandwiched between magnetic layers having different coercive forces.

A spin valve type GMR material has a structure in which a ferromagnetic layer, a nonmagnetic conductive layer, a ferromagnetic layer, and an antiferromagnetic layer are stacked, and the antiferromagnetic layer is formed of one ferromagnetic layer. The magnetization of the ferromagnetic layer is pinned by magnetic coupling. For this reason, the antiparallel magnetization state is stabilized in a wide magnetic field region, the magnetoresistance change ratio (MR ratio) is high, and the magnetic field sensitivity is high.

[0006]

In the magnetoresistive element using the spin valve type GMR material as described above, in order to obtain high magnetic field detection sensitivity, the MR ratio and the uniaxial anisotropic magnetic field (Hua) are high. It is desirable that the coercive force (Hc) of the magnetic field reversal (free) layer be low, and various studies have been made from such a viewpoint. However, a conventional magnetoresistive element using a GMR material exhibits a somewhat large MR ratio and a good magnetic field sensitivity, but is still insufficient, and is still insufficient. Development is required.

An object of the present invention is to provide a magnetoresistive element having a high MR ratio and good magnetic field sensitivity.

[0008]

According to the present invention, there is provided a magnetoresistance effect element comprising: an underlayer having convex portions dispersed in an island shape; a ferromagnetic layer and a nonmagnetic layer laminated on the underlayer. And a magnetoresistive film having a structure in which conductive layers are stacked.

According to the present invention, since the magnetoresistive film is provided on the underlayer in which the convex portions are dispersed in an island shape, the unevenness of the underlayer is taken over, and the ferromagnetic effect in the magnetoresistive film is taken over. Irregularities are formed at the interface between the layer and the nonmagnetic conductive layer. Since the unevenness is formed at the interface between the ferromagnetic layer and the non-magnetic conductive layer in this way, more electrons flowing in the magnetoresistive film pass through the interface, and are more affected by magnetic scattering,
As a result, it is considered that a large MR ratio and good magnetic field sensitivity are exhibited.

In the present invention, the underlayer may be a continuous layer or a discontinuous layer. That is, it may be continuous or discontinuous at the bottom of the protrusion of the underlayer. That is, the underlayer may be such that only the protrusions are discontinuously scattered.

In the present invention, the underlayer may be formed of a plurality of layers. For example, an underlayer may be formed by providing a second underlayer on the first underlayer. In such a case, a protrusion may be provided on the second underlayer. In particular, by forming the first underlayer and the second underlayer from materials having a non-solid solution relationship with each other, it is possible to form island-shaped projections in the second underlayer. it can. For example, a first underlayer made of Ta is formed, and C is formed on the first underlayer.
When a second underlayer is formed thereon by a sputtering method or the like using a material which is insoluble in Ta such as u, an island-shaped convex portion is formed in the second underlayer. be able to. In addition, Ag-Co, Cu-Fe, and the like may be used as such a material having a non-solid solution.

The manufacturing method of the present invention is characterized in that an underlayer is formed from such a first underlayer and a second underlayer. That is, in the manufacturing method of the present invention, a step of forming a first underlayer on a substrate and a material having a non-solid solution relationship with the material of the first underlayer are formed on the first underlayer. Forming a second underlayer having island-shaped protrusions by using a magnetic layer, and a magnetoresistive layer having a structure in which a ferromagnetic layer and a nonmagnetic conductive layer are laminated on the second underlayer. Forming an effect film.

The size and shape of the protrusions of the underlayer according to the present invention are not particularly limited as long as moderate asperities can be formed at the interface between the ferromagnetic layer and the nonmagnetic conductive layer of the magnetoresistive film. However, for example, a projection having a height of 0.5 to 10 nm and a diameter of about 1 to 500 nm in the film surface direction is preferable. Further, it is preferable that the formation density of the protrusions is such that the average distance between the centers of the protrusions is about 5 to 300 nm.

In the present invention, the magnetoresistive film laminated on the underlayer is a magnetoresistive film having a structure in which a ferromagnetic layer and a nonmagnetic conductive layer are laminated. Examples of such a magnetoresistive film include a spin valve type magnetoresistive film, a coercive force difference type magnetoresistive film, and an artificial lattice type magnetoresistive film.

The spin valve type magnetoresistive film comprises a first ferromagnetic layer and a second ferromagnetic layer, and a non-magnetic conductive layer provided between the first ferromagnetic layer and the second ferromagnetic layer. A magnetoresistive film comprising a layer and an antiferromagnetic layer magnetically coupled to one of the first ferromagnetic layer and the second ferromagnetic layer.

The coercive force difference type magnetoresistive effect film includes a first ferromagnetic layer, a second ferromagnetic layer, the first ferromagnetic layer and the second ferromagnetic layer.
And a non-magnetic conductive layer provided between the two ferromagnetic layers, wherein the first ferromagnetic layer and the second ferromagnetic layer have substantially different coercive forces.

The artificial lattice type magnetoresistive film is a magnetoresistive film having a laminated structure in which a ferromagnetic layer and a nonmagnetic conductive layer are repeatedly laminated. The method for forming each of the underlayer and the magnetoresistive film in the present invention is not particularly limited, and a general thin film forming method such as a sputtering method, a vacuum evaporation method, and a CVD method can be employed.

The ferromagnetic layer of the magnetoresistive film according to the present invention is not particularly limited as long as it is formed of a ferromagnetic material. For example, NiFe, Co, CoNiF
e, can be formed from a ferromagnetic material such as CoFe.

The non-magnetic conductive layer of the magnetoresistive film in the present invention is not particularly limited as long as it is formed of a non-magnetic material having excellent conductivity. For example, the non-magnetic conductive layer may be formed of Cu, Ag or the like. Can be.

The antiferromagnetic layer of the magnetoresistive film according to the present invention is not particularly limited as long as it is formed of an antiferromagnetic material. For example, antiferromagnetic layers such as FeMn, IrMn and NiMn can be used. It can be formed from an alloy or an oxide antiferromagnetic material such as NiO, CoO, and Fe ₂ O ₃ .

The magnetoresistance effect element according to the present invention is generally formed on a substrate. In general, the material of the substrate is not particularly limited as long as it is non-magnetic.
Substrates such as TiC, Al ₂ O ₃ , and glass can be used.

[0022]

FIG. 1 is a sectional view showing an embodiment of a magnetoresistive element according to the present invention. A first underlayer 2 (6.5 nm thick) made of Ta is formed on a (100) plane of a substrate 1 made of Si. On the first underlayer 2, a second underlayer 3 made of Cu is formed. In the second underlayer 3, convex portions 3a are formed in an island-like manner. In this embodiment, the bottom of the projection 3a is continuous. First underlayer 2 and second underlayer 3
Thus, the underlayer 10 is formed.

On the second underlayer 3, a first ferromagnetic layer 4 made of CoFe (5 nm thick), a nonmagnetic conductive layer 5 made of Cu (2.5 nm thick), and a 2
And a ferromagnetic layer 7 (thickness: 15 nm) made of IrMn.

The first ferromagnetic layer 4, the nonmagnetic conductive layer 5, the second ferromagnetic layer 6, and the antiferromagnetic layer 7 constitute a spin-valve type magnetoresistive film. The first underlayer 2, the second underlayer 3, and the layers 4 to 6 constituting the magnetoresistive film are all formed by an ion beam sputtering (IBS) method.

FIG. 2 is a sectional view showing a state after the first underlayer 2 and the second underlayer 3 are formed on the substrate 1 in the embodiment shown in FIG. As shown in FIG. 2, on the second underlayer 3 formed on the first underlayer 2, a particulate convex portion 3 a is formed. In this embodiment, as described above, Ta is used as the material of the first underlayer 2 and Cu is used as the material of the second underlayer 3. Ta and Cu have a non-solid solution relationship with each other. As described above, when the materials of the first underlayer 2 and the material of the second underlayer 3 are insoluble in each other, the materials of FIG.
The second underlayer 3 in which the particle-like protrusions 3a as shown in FIG.

FIG. 3 is an atomic force microscope photograph showing a state after the first underlayer 2 is formed on the substrate 1. 3 to 5 are all atomic force microscope photographs,
As is clear from the dimensions described, the magnification in the height direction is increased, and the dimensions in the height direction are emphasized.

FIG. 4 is an atomic force microscope photograph showing a state after the second underlayer 3 made of Cu is formed on the first underlayer 2 made of Ta shown in FIG. The underlayer 3 shown in FIG. 4 is a thin film formed when the Cu film thickness conversion rate is set to 1.5 nm. Here, the Cu film thickness conversion rate is a deposition rate at which a thin film having such a film thickness can be formed after 30 seconds if the thin film has a flat surface. In the case of FIG. 4 where the Cu film thickness conversion rate is set to 1.5 nm, the height of the projection 3a is about 7 nm, and the diameter (diameter) of the projection 3a along the film surface direction is 60 to 120 nm.
Met. The average distance between the centers of the projections 3a is:
It was 0.1 to 0.3 μm.

FIG. 5 shows a Cu film thickness conversion rate of 2.25 n.
6 is an atomic force micrograph showing the second underlayer 3 and its convex portion 3a when m is set. As shown in FIG. 5, a larger projection 3a is formed than the projection 3a shown in FIG. Also, it can be seen that the formation density of the projections 3a is low.

FIG. 6 shows a Cu film thickness conversion rate of 0.75 nm.
FIG. 2 is a diagram showing an MR curve (a curve showing a change in an MR ratio with respect to an external magnetic field) of the magnetoresistive effect element shown in FIG. 1 when a second underlayer 3 is formed. As is clear from FIG. 6, the maximum MR ratio is 9.2%, the uniaxial anisotropic magnetic field (Hua) is 200 Oe, and the coercive force (H
c) is 25 Oe. Therefore, it can be seen that a high MR ratio and good magnetic field sensitivity are exhibited.

FIGS. 7 to 9 show various magnetoresistive elements manufactured by changing the Cu film thickness conversion rate when forming the second underlayer 3 in the embodiment shown in FIG. FIG. 4 is a diagram showing characteristics of a magnetoresistive element according to the present invention. FIG.
1 shows the MR ratio (■) and ΔR (□) of the magnetoresistive effect element, both of which are represented by normalized values where the value when the underlayer 10 is not formed in FIG. FIG. 8 similarly shows Hc (O) and Hua (●) of the magnetoresistive effect element with normalized values. FIG. 9 shows the diameter of the convex portion in the second underlayer in the film surface direction.

As is clear from FIG. 7, all the embodiments according to the present invention show a high MR ratio. In particular, when the Cu film thickness conversion rate is high near 0.75 nm, the MR
The ratio and ΔR are obtained. In addition, annealing (260 ° C.
× 60 minutes), no decrease in the MR ratio was observed.

In the embodiment shown in FIG. 1, a spin valve type magnetoresistive film is used as the magnetoresistive film. In the present invention, for example, a magnetoresistive film in which the spin-valve magnetoresistive films shown in FIG. 1 are stacked in reverse order may be used. That is, a magnetoresistive film in which the antiferromagnetic layer 7, the second ferromagnetic layer 6, the nonmagnetic conductive layer 5, and the first ferromagnetic layer 4 are stacked in this order may be used. Further, a dual spin valve type magnetoresistive film may be used. Examples of such a dual spin valve type magnetoresistive film include an antiferromagnetic layer / ferromagnetic layer / nonmagnetic conductive layer / ferromagnetic layer (free layer) / nonmagnetic conductive layer / ferromagnetic layer / antiferromagnetic layer. One having a laminated structure of a magnetic layer is exemplified.

FIG. 10 is a sectional view showing another embodiment of the magnetoresistive element according to the present invention. In the embodiment shown in FIG. 10, a coercive force difference type magnetoresistive film is used as the magnetoresistive film. A first ferromagnetic layer 14 of Co (film thickness 5) is formed on the second underlayer 3 having the convex portions 3a.
0 °), the nonmagnetic conductive layer 15 made of Cu (film thickness 25
Å) and the second ferromagnetic layer 16 made of Fe (film thickness 50
Å) are sequentially formed by the IBS method and stacked. In this magnetoresistive film, the nonmagnetic conductive layer 15
A first ferromagnetic layer 14 and a second ferromagnetic layer 16 having different coercive forces are provided on both sides of the magnetoresistive effect film to form a coercive force difference type magnetoresistive film.

FIG. 11 is a sectional view showing a magnetoresistive element according to still another embodiment of the present invention. In the embodiment shown in FIG. 11, an artificial lattice type magnetoresistive film is provided as the magnetoresistive film. A ferromagnetic layer 24 made of Co (film thickness 2) is formed on the second underlayer 3 having the convex portions 3a.
0 °) and a nonmagnetic conductive layer 25 made of Cu (film thickness: 20 °)
Are repeatedly laminated a plurality of times. In this embodiment, 1
It is repeatedly laminated five times. The magnetoresistive film of this embodiment has a so-called artificial lattice type magnetoresistive film in which antiferromagnetic coupling exists between the ferromagnetic layers 24 on both sides of the nonmagnetic conductive layer 25.

FIG. 12 is a sectional view showing still another embodiment of the magnetoresistive element according to the present invention. In the embodiment shown in FIG. 12, an underlayer 20 having convex portions 20a dispersed in an island shape on a substrate 1 is formed. On this underlayer 20, a spin-valve magnetoresistive film similar to the embodiment shown in FIG. Thus, in the present invention, the underlayer may be formed from one layer.

FIG. 13 is a sectional view showing still another embodiment of the magnetoresistive element according to the present invention. On the substrate 1, an underlayer 30 having convex portions 30a dispersed in an island shape is formed. In this embodiment, the underlayer 30 is a discontinuous thin film, and is discontinuous at the bottom of the projection 30a with the adjacent projection. Thus, in the present invention, a base layer in which the protrusions 30a are discontinuously scattered may be used. In this embodiment, such a discontinuous underlayer 3
A spin-valve magnetoresistive film is formed on the reference numeral 0 as in the embodiment shown in FIG.

In the above embodiment, the spin-valve type, coercive force difference type and artificial lattice type magneto-resistance effect films have been described as examples of the magneto-resistance effect film, but the present invention is not limited to this. Instead, the present invention can be applied to a magnetoresistive element including a magnetoresistive film having a structure in which a ferromagnetic layer and a nonmagnetic conductive layer are stacked.

[0038]

According to the present invention, a magnetoresistive element having a high MR ratio and a high uniaxial anisotropic magnetic field and excellent magnetic field sensitivity can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a magnetoresistance effect element according to the present invention.

FIG. 2 is a sectional view showing a state after a base layer is formed in the embodiment shown in FIG. 1;

FIG. 3 is an atomic force microscope photograph showing a state of a thin film of a first underlayer formed on a substrate.

FIG. 4 is an atomic force microscope photograph showing a state of a thin film of a second underlayer formed on the first underlayer.

FIG. 5 is an atomic force microscope photograph showing a state of a thin film of a second underlayer formed on the first underlayer.

FIG. 6 is a view showing an MR curve of the magnetoresistive element of the embodiment shown in FIG. 1;

FIG. 7 is a diagram showing a relationship between an MR ratio and ΔR and a conversion rate of a Cu film thickness of a second underlayer.

FIG. 8 is a diagram showing a relationship between Hc and Hua and a Cu film thickness conversion rate of a second underlayer.

FIG. 9 shows the diameter of the protrusion of the second underlayer and the Cu of the second underlayer.
The figure which shows the relationship with a film thickness conversion rate.

FIG. 10 is a sectional view showing another embodiment of the magnetoresistance effect element according to the present invention.

FIG. 11 is a sectional view showing still another embodiment of the magnetoresistive element according to the present invention.

FIG. 12 is a sectional view showing still another embodiment of the magnetoresistance effect element according to the present invention.

FIG. 13 is a sectional view showing still another embodiment of the magnetoresistance effect element according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... 1st underlayer 3 ... 2nd underlayer 3a ... convex part of 2nd underlayer 4 ... 1st ferromagnetic layer 5 ... nonmagnetic conductive layer 6 ... 2nd ferromagnetic layer 7 ... Anti-ferromagnetic layer 10 ... Underlayer 14 ... First ferromagnetic layer 15 ... Nonmagnetic conductive layer 16 ... Second ferromagnetic layer 20 ... Underlayer 20a ... Underlayer convex portion 24 ... Ferromagnetic layer 25 ... Non Magnetic conductive layer 30... Underlayer 30 a.

Claims (10)

[Claims] An underlayer in which convex portions are dispersed in an island shape, and a magnetoresistive film having a structure in which a ferromagnetic layer and a nonmagnetic conductive layer are stacked on the underlayer. A magnetoresistive effect element comprising: 2. The magnetoresistive element according to claim 1, wherein the underlayer is a continuous underlayer at the bottom of the projection. 3. The magnetoresistance effect element according to claim 1, wherein the underlayer is a discontinuous underlayer at the bottom of the projection. 4. The method according to claim 1, wherein the underlayer is a second underlayer on the first underlayer.
2. The magnetoresistance effect element according to claim 1, wherein the underlayer is provided with the underlayer, and the protrusion is provided on a second underlayer. 3. 5. The magnetoresistive element according to claim 4, wherein the first underlayer and the second underlayer are each formed of a material having a non-solid solution relationship with each other. 6. The magnetoresistive element according to claim 5, wherein the first underlayer is formed of Ta, and the second underlayer is formed of Cu. 7. The magneto-resistance effect film includes a first ferromagnetic layer and a second ferromagnetic layer, the first ferromagnetic layer and the second ferromagnetic layer.
A nonmagnetic conductive layer provided between the ferromagnetic layers of
7. A spin-valve type magnetoresistive film comprising a ferromagnetic layer and an antiferromagnetic layer magnetically coupled to one of the second ferromagnetic layer. The magnetoresistive effect element as described in the above. 8. The magneto-resistance effect film includes a first ferromagnetic layer and a second ferromagnetic layer, the first ferromagnetic layer and the second ferromagnetic layer.
A non-magnetic conductive layer provided between the ferromagnetic layers of the first and second ferromagnetic layers, wherein a coercive force difference type magnetoresistive film in which the first ferromagnetic layer and the second ferromagnetic layer have substantially different coercive forces. Certain claim 1
7. The magnetoresistive element according to any one of items 1 to 6. 9. The magnetoresistive film according to claim 1, wherein said magnetoresistive film is an artificial lattice type magnetoresistive film in which a ferromagnetic layer and a nonmagnetic conductive layer are repeatedly laminated. Effect element. 10. A step of forming a first underlayer on a substrate, and using a material which has a non-solid solution relationship with a material of the first underlayer on the first underlayer. Forming a second underlayer having island-shaped projections; and forming a magnetoresistive film having a structure in which a ferromagnetic layer and a nonmagnetic conductive layer are stacked on the second underlayer. And manufacturing the magnetoresistive effect element.