JP2806549B2 - Magnetoresistance effect element - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive element which detects a magnetic field using a ferromagnetic magnetoresistance effect and has a linear response to the magnetic field.

[Conventional technology]

In general, when a magnetoresistive element is used as a high-sensitivity magnetic sensor exhibiting a linear response, an angle θ (bias angle) between a sense current I flowing through the magnetoresistive element and magnetization M of the magnetoresistive element is determined. Predetermined value (preferably 45
(Degree).

Various methods have been disclosed as the bias means.

For example, a magnetoresistive head (a magnetic head having a magnetoresistive effect element) disclosed in Japanese Utility Model Application No. 59-48201 discloses a nonmagnetic layer formed on a ferromagnetic layer having a magnetoresistive effect formed on a substrate. A structure in which a conductor layer and an amorphous soft magnetic material layer are sequentially laminated has a good bias angle θ.
To realize a magnetoresistive element having excellent linear response.

That is, as shown in FIG. 5, a ferromagnetic layer 52 (for example, having a film thickness of 200 to 500) is formed on an insulating substrate 51 made of glass, ferrite or the like and having a smooth surface by sputtering or vapor deposition.
Ni Ni-Fe alloy) is formed, and Ti, M
A magnetoresistive effect having a structure in which a nonmagnetic conductor layer 53 of o, Cr, Ta, etc. is formed by the same method, and an amorphous soft magnetic layer 54 is formed on the nonmagnetic conductor layer 53 by the same method. An element is disclosed. Here, the current terminal 55 is a current terminal for supplying a current to the laminate of the ferromagnetic layer 52, the nonmagnetic conductor layer 53, and the amorphous soft magnetic layer 54.

In the specification of Japanese Patent Application No. 62-312859, the order of lamination of the three layers in FIG. 5 was changed to an amorphous soft magnetic layer 54, a nonmagnetic conductor layer 53, and a ferromagnetic layer 52. Although an effect element is disclosed, the principle of bias application is exactly the same as that of the above-described magnetoresistance effect element.

[Problems to be solved by the invention]

The following conventional magnetoresistance effect element has the following points.

(A) Since a non-magnetic conductor layer 53 is made of a metal material having a small specific resistance, such as Ti or Mo, a considerable amount of the sensor current I is diverted to the non-magnetic conductor layer 53, and substantially the ferromagnetic layer The amount of current for sensing the resistance change flowing through 52 decreases. As a result, the sense current I is increased in order to obtain a required amount of output as a magnetoresistive element, and heat is generated due to the increase in current, thereby deteriorating the characteristics of the magnetoresistive element.

(B) In order to overcome the above-mentioned disadvantage, a method of suppressing the shunt of the sense current by using a nonmagnetic insulator layer such as SiO ₂ instead of the nonmagnetic conductor layer 53 is considered. However, in this method, since the layer thickness is small (200 to 400 °), pinholes are liable to occur, and there is a possibility that unnecessary magnetic coupling is induced between the ferromagnetic layer 52 and the amorphous soft magnetic layer 54. is there. When the ferromagnetic layer 52 exists between the nonmagnetic insulator layer and the substrate 51, the ferromagnetic layer 2 and the current terminal 55 are provided to apply the sense current I to the ferromagnetic layer 52. Must be in direct contact with As a result, the manufacturing process of the magnetoresistance effect element has become very complicated.

An object of the present invention is to provide a magnetoresistive element capable of solving the above-mentioned problems and realizing a desired magnetoresistive effect by supplying a sufficient sense current to a ferromagnetic layer and easily manufacturing the same. is there.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a laminated ferromagnetic layer and an amorphous soft magnetic layer having a power terminal for applying a sense current at both ends thereof, and a ferromagnetic layer and an amorphous soft magnetic layer. And a non-magnetic conductor layer interposed between the non-magnetic conductor layer and the non-magnetic conductor layer.

[Action]

According to the present invention, since most of the sense current flows through the ferromagnetic layer (about 25 μΩ · cm) since carbon having a high specific resistance (about 350 μΩ · cm) is used as the nonmagnetic conductor layer, As a metal material having a low specific resistance (for example, T
i: 50 μΩ · cm), a large magnetic field detection output can be obtained even with the same sense current value. Further, a carbon (carbon) film having a graphite structure is generally dense, does not generate pinholes even in an extremely thin film, and effectively blocks magnetic coupling between the ferromagnetic inner layer and the amorphous soft magnetic material layer. Also, in the configuration in which the ferromagnetic layer is interposed between the carbon film and the substrate, the thickness of the carbon film is 200 to 400 mm.
Therefore, it is not necessary to make the ferromagnetic layer and the current terminal directly contact each other.

〔Example〕

 Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a longitudinal sectional view of a magnetoresistive element according to a first embodiment of the present invention.

This magnetoresistive element is formed by stacking a ferromagnetic layer 2, a nonmagnetic conductor layer 3, and an amorphous soft magnetic layer 4 on a glass substrate 1 in this order.
It has a structure in which a pair of current terminals 5, 5 are mounted on the uppermost amorphous soft magnetic layer 4.

The ferromagnetic layer 2 is a permalloy film formed by using a deposition method at a temperature of the substrate 1 of 300 to 350 ° C. This permalloy film is a NiFe film, the thickness of which is set to 400 °, and the weight percentages of Ni and Fe are set to 82% and 18%, respectively. Further, a magnetic field of 100 Oe is applied during the formation of the permalloy film, and the uniaxial magnetic anisotropy is imparted to the NiFe film.

The nonmagnetic conductor layer 3 is a 200-nm-thick carbon film formed on the ferromagnetic layer 2 by a sputtering method. With this carbon film, the specific resistance becomes about 350 μΩ · cm.

The amorphous soft magnetic layer 4 is a CoZrMo film having a thickness of 300 ° formed on the nonmagnetic conductor layer 3 by a sputtering method. A magnetic field of 100 Oe is applied during the formation of the amorphous soft magnetic layer 4 to impart uniaxial anisotropy to the amorphous soft magnetic layer 4. An Au film is formed on the amorphous soft magnetic layer 4 by a vapor deposition method.

The current terminals 5, 5 are formed by forming a photoresist pattern on the amorphous soft magnetic layer 4 and performing etching. Specifically, a predetermined photoresist pattern is formed on the laminates 3, 4, and 5, ion etching is performed in an Ar gas atmosphere, and the laminates 3 to 5 are 50 μm long and 5 μm wide.
m is processed into a rectangular pattern. Here, the etching conditions are an acceleration voltage of 500 V and an Ar gas output of 1 × 10 ⁻⁴ Torr. Then, a photoresist pattern is formed on the rectangular laminates 3 to 5, and the current terminals 5, 5 are formed by performing selective chemical etching of the Au layer on the surface.

In this magnetoresistive element, the sense current I supplied from the current terminal 5 mainly flows through the ferromagnetic layer 2 having the smallest specific resistance. The sense current I flowing through the ferromagnetic layer 2 generates a magnetic field that passes through the plane of the amorphous soft magnetic layer 4 and is perpendicular to the direction of the sense current I. The magnetization direction of the amorphous soft magnetic layer 4 is rotated by this magnetic field. Thereby, the magnetization in the amorphous soft magnetic layer 4 generates a magnetic field around the amorphous soft magnetic layer 4 in a direction opposite to the direction of the magnetic field, and a part of the magnetic field is applied to the ferromagnetic layer 2. Is done. This bias magnetic field rotates the magnetization of the ferromagnetic layer 2 with respect to the sense current I, and realizes a linear response by setting the bias angle θ of the ferromagnetic layer 2 to a predetermined value (ideally 45 degrees). I do.

In the above magnetoresistive effect element, the sense current I is 10
When a magnetic field was detected by flowing mA, the resistance change rate Δρ / ρ of the entire magnetoresistance effect element was 2.2%, and the maximum value voltage change ΔV was 13.4 mV. In order to compare this result with a conventional example, a Ti deposited film, which is a conventional material, was used for the nonmagnetic conductor layer 3,
With respect to other layers and patterning, a magnetoresistive element was manufactured which was exactly the same as the previous example. In this magnetoresistive effect element, when the sensor current I was also passed at 10 mA and the magnetic field was detected, the rate of change in resistance of the magnetoresistive effect element Δ
ρ / ρ was 1.8%, and the maximum voltage change ΔV was 1.4 mV.
That is, in the magnetoresistive effect element according to the present embodiment, a magnetic field detection output about 18% larger than that of the related art was realized.

FIG. 2 is a longitudinal sectional view of a magnetoresistive element according to a second embodiment of the present invention.

The magnetoresistive element of this example has a structure in which an amorphous soft magnetic layer 14, a nonmagnetic conductor layer 13, and a ferromagnetic layer 12 having an Au layer on the upper surface are laminated on a glass substrate 11. . In addition, the film forming method, patterning, operation, and the like of each layer are the same as those of the magnetoresistive element of FIG. In the magnetoresistive element of this example, a high magnetic field detection output was realized as in the magnetoresistive element of FIG.

FIG. 3 is a longitudinal sectional view of a magnetoresistive element according to a third embodiment.

The magnetoresistive element of this embodiment differs from the magnetoresistive element of FIG. 1 in that a ferromagnetic layer 22, a nonmagnetic conductor layer 23, and an amorphous soft magnetic layer 24 are laminated on a glass substrate 21. It has the same structure,
It differs from the magnetoresistive element of FIG. 1 in that the current terminals 25, 25 are formed as follows.

This laminate is formed by forming a predetermined photoresist pattern on the laminates 22 to 24 and performing ion etching.
22 to 24 are processed into a rectangular pattern having a length of 50 μm and a width of 5 μm, and then Au is deposited on the rectangular laminates 22 to 24 (the film thickness is 0.5 μm), and then a photo is deposited on the Au deposited film. Current terminals 25, 25 were formed by forming a resist pattern and performing selective chemical etching.

Also in the magnetoresistive element of this example, a high magnetic field detection output was realized similarly to the magnetoresistive elements of FIGS. 1 and 2.

FIG. 4 is a longitudinal sectional view of a magnetoresistive element according to a fourth embodiment.

The magnetoresistive effect element of this example has a structure in which an amorphous soft magnetic material 34, a nonmagnetic conductor layer 33, and a ferromagnetic layer 32 are sequentially stacked on a glass substrate 31. Other film forming methods, patterning, operations, and the like of each layer are the same as those of the magnetoresistive element of FIG. Also in the magnetoresistive element of this example, a high magnetic field detection output was realized as in the magnetoresistive element of FIG.

〔The invention's effect〕

The magnetoresistance effect element of the present invention has the following effects because it is configured as described above.

(A) Since carbon having a large specific resistance is used for the nonmagnetic conductor layer, most of the sense current flows to the ferromagnetic layer. As a result, a large magnetic field detection output can be obtained with the same sense current value as compared with a conventional magnetoresistive effect element using a metal material having a small specific resistance for the nonmagnetic conductor layer.

(B) Since the carbon layer is dense, pinholes are less likely to occur during film formation. Therefore, the magnetic coupling between the ferromagnetic layer and the nonmagnetic conductor layer is effectively cut off.

(C) Since a sufficient current flows in the thickness direction of the carbon layer,
The sense current can be supplied to the ferromagnetic layer without directly attaching the current terminal to the ferromagnetic layer.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a magnetoresistive element according to a first embodiment of the present invention, and FIGS. 2 to 4 are longitudinal sections of a magnetoresistive element according to second to fourth embodiments of the present invention. FIG. 5 is a perspective view showing a conventional magnetoresistive element. 1,11,21,31 ・ ・ ・ substrate 2,12,22,32 ・ ・ ・ ferromagnetic layer 3,13,23,33 ・ ・ ・ non-magnetic conductor layer 4,14,24,34 ・ ・ ・ non Amorphous soft magnetic layer 5,15,25,35 ・ ・ ・ Current terminal

Claims (1)

(57) [Claims] 1. A ferromagnetic material layer and an amorphous soft magnetic material layer having power terminals for applying a sense current at both ends thereof, and a ferromagnetic material layer and an amorphous soft magnetic material layer A magnetoresistive element including a nonmagnetic conductor layer interposed therebetween, wherein the nonmagnetic conductor layer is made of a carbon film.