JPS614287A - Magnetoresistance effect element - Google Patents

Abstract

PURPOSE:To suppress a demagnetizing field sufficiently by a simple constitution, to reduce hysteresis phenomenon and to manufacture a highly sensitive magnetoresistance effect element at a low cost, by providing a non-magnetic insulating layer on a stripe shaped high permeability magnetic film, and providing a magnetoresistance-effect-film stripe on said insulating layer. CONSTITUTION:On a substrate 5, magnetic focusing films 2 and 2' comprising a high permeability magnetic material such as permalloy are evaporated to a thickness of several mum. A non-magnetic insulating layer 3 comprising a material such as SiO2 and Al2O3 is formed thereon to a thickness of several hundreds mum. Thereafter, nickel-cobalt alloy, nickel-cobalt-iron alloy and the like are evaporated as a magnetoresistance-effect-film stripe 1 to a thickness of several hundreds - several thousands Angstrom in a transverse magnetic field. The stripe 1 and the magnetic focusing films 2 and 2' are constituted in reverse patterns. The manufacturing processes are not complicated. The highly sensitive magnetoresistance-effect element can be readily manufactured at a low cost.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to magnetic sensors used in encoders, magnetic recording devices, magnetic bubble memories, etc. Concerning becoming.

2. Description of the Related Art Magnetoresistive elements that use the magnetoresistive effect of ferromagnetic alloy films have come to be widely used as magnetic sensors such as encoders, various magnetic recording devices, and magnetic bubble memories.

By the way, the ferromagnetic magnetic effect film in this magnetoresistive element has conventionally been made of 82%Ni-18%F by weight.
Permalloy, an e-alloy, is widely used. The film thickness at this time is generally in the range of 25 to 400 nm, but in this case, the film thickness is in the range of 30 to 400 nm.
Ferromagnetic magnetic effect ΔR/R due to 40 nm permalloy film
is about 2.5%, and when the film thickness is 300 to 400 nm, Δ
R/R is approximately 3.5 inches.

On the other hand, IEEE Transactfonson M
agne-tics MAG-11, (1975) 1
018-1038 contains a 92-layer N1-8 wt% Fe alloy, (70 to 90) wt% Ni-(30
~10) Weight ft%c.

Alloy, 67 wt% Ni-30 wt% Co-3 wt% Cr
Alloys, etc. are disclosed.

Here, to explain the general shape of the magnetoresistive film in the above-mentioned magnetic sensor etc., it is used as stripe 1 as shown in Figure 2, and the detection magnetic field Hx is applied to it in the direction shown by the arrow. It will be done. and,
The thickness d of the stripe 1 is 2 (1-50 nm, the width W is 5-40 μm1, and the length L is -100-30°0″°
The distance 1f"r6D .'"0#L" is sufficiently larger than the width W, and the width W is also sufficiently larger than the thickness d.

By the way, it goes without saying that it is desirable for the magnetoresistive film used in such a magnetoresistive element to have a large ferromagnetic magnetoresistive effect, but in addition to this, the following two requirements must also be met. It is desirable that the requirements are met.

(1) Good magnetic sensitivity. That is, the magnetic field Hx to be detected
Even if the ferromagnetic resistance is small, it should exhibit a sufficient ferromagnetic resistance effect.

(2) There is little hysteresis phenomenon with respect to the magnetic field Hx. That is, it must have uniaxial magnetic anisotropy with the length L direction as the axis of easy magnetization.

However, none of the conventional magnetoresistive films described above satisfies these requirements, and for this reason, there have been proposals to devise the structure of magnetoresistive elements to satisfy these requirements. For example, this has been proposed in Japanese Unexamined Patent Publication No. 56-905-77, and the structure of this proposed device will be explained with reference to FIG.

In FIG. 3, 1 is a stripe of a magnetoresistive film, 2.2' and 4.4' are high permeability magnetic films, 3 is a nonmagnetic insulating layer, and 5 is a substrate. 'High permeability magnetic film 2.2'
are arranged adjacent to the stripe 1 with a predetermined gap Gf maintained in the detection magnetic field HxX direction.

The nonmagnetic insulating layer 3 is provided so as to cover the stripes 1 and the high permeability magnetic films 2.2'i on the surface of the substrate 50, and then cover the gaps G with the stripes 1.

The high permeability magnetic film 4,4' is provided on the nonmagnetic insulating layer 3 so as to span the stripe 1 and the high permeability magnetic films 2, 2' and cover the gap G.

According to this structure, the demagnetizing field within the stripe 1 is reduced by the high magnetic permeability magnetic films 2.2' and 4.4' adjacent to the stripe 1, and as a result, the demagnetizing field within the stripe 1 is reduced in the width direction (X direction). ) The detection sensitivity to the detection magnetic field Hx applied to the magnetic field Hx can be increased.

However, in this structure, since the stripe 1 is covered with the non-magnetic insulating layer 3, extra manufacturing processes such as drilling holes in the non-magnetic insulating layer 3 are required to take out the connection terminals, resulting in a high cost. Since the magnetic permeability film is formed on the surface of the substrate 50 and the surface of the nonmagnetic insulating layer 3, there is a drawback that the manufacturing process of the element is complicated and the cost is likely to increase.

[Purpose of the invention]

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, to provide a low-cost, high-sensitivity magnetoresistive element that can sufficiently suppress the demagnetizing field and reduce the hysteresis phenomenon with a simple structure.

[Summary of the invention]

In order to achieve this object, the present invention provides a non-magnetic insulating layer on a strip-shaped high permeability magnetic film consisting of an inverse pattern of magnetoresistive film stripes, and forms magnetoresistive film stripes on this insulating layer. By providing this, the gap between the stripe and the strip-shaped high permeability magnetic film can be made sufficiently narrow in a controlled manner.

[Embodiments of the invention]

EMBODIMENT OF THE INVENTION Hereinafter, the magnetoresistive effect element according to the present invention will be explained in detail with reference to illustrated embodiments.

FIG. 1 shows an embodiment of the present invention, in which the magnetoresistive film stripe 1, high permeability magnetic film 2, 2', nonmagnetic insulating layer 3, substrate 5, etc. are the same as in the conventional example shown in FIG. In addition, since the high permeability magnetic film 2.2' functions to focus the detection magnetic field,
These are called magnetic field focusing films. The device according to the embodiment shown in FIG. 1 is manufactured, for example, as follows.

First, a substrate 5 with a smooth surface is made of a material such as silicon, ceramic, or glass, and a magnetic focusing film 2.2' made of a high permeability magnetic material such as permalloy is deposited on it to a thickness of several μm. , on top of that 5i02 and Al2
A non-magnetic insulating layer 3 made of a material such as O3 is formed to a thickness of several 100 Mengestroms.

After this, magnetoresistive film stripe 1! -Nikke A
/ -ko/< A/ ) Alloy, nickel-coba A/
) -Iron-alloy's number N & InL thousands''g''°-''
Deposit to 0 thickness. At this time, K is generally deposited using a magnetic field evaporation method in which evaporation is performed while a magnetic field is applied. toggle and add,
If we adopt the so-called switching orthogonal magnetic field deposition method,
Detection sensitivity can be further increased.

Here, the stripe 1 and the magnetic field focusing film 2.2' have a so-called reverse pattern in which their planar shapes complement each other and form a continuous plane. For example, when such a magnetoresistive element is configured as a magnetic sensor of an encoder, the planar shape of the portion including the stripe 1 and its corresponding terminal is as shown in FIG. It is arranged in a grid pattern. Therefore, the relationship between the stripe 1 and the magnetic field focusing film 2.2' at this time is as shown in FIGS. 5(a) and 5(b), and this is called a reverse pattern.

Figure 6 shows the characteristics of the embodiment shown in Figure 1.
The solid line A shows the resistance change rate ΔR/ΔRmax characteristic of the magnetoresistive stripe 1 with respect to the detected magnetic field Hx, and the broken line B shows the characteristic when the magnetic field focusing film 2.2' is removed for comparison. Therefore, the thickness of stripe 1 is 0.04
The thickness of the nonmagnetic insulating layer 3 is 0.4 μm, and the thickness of the magnetic field focusing film is 2 μm.

As is clear from FIG. 6, in characteristic A according to the embodiment of the present invention, the magnetic field HxO value at which the width value ΔR/ΔRmax = 0.5 is about 50% of that in characteristic B, resulting in remarkable sensitivity. You can get an increase in

Now, considering the reason why high sensitivity can be obtained by the embodiment of the present invention, in the embodiment of the present invention, as shown in FIG. This is thought to be due to the fact that the thickness of the magnetic field focusing film 2.2' can be made extremely small, close to the thickness of the nonmagnetic insulating layer 3, and the resistance to the flow of magnetic flux from the magnetic field focusing film 2.2' to the stripe 1 is sufficiently small. It will be done.

What is important at this time is that the magnetic field focusing film 2°-2'
By selecting the thickness of the magnetic field focusing film 2, as shown in FIG.
If the thickness of stripe 2' is the same as the thickness of stripe 1, no increase in sensitivity will be observed. Therefore, it is desirable to select the thickness of the magnetic field focusing film 2.2' to be thicker than the thickness of the stripe 1, and preferably to be at least the sum of the thickness of the stripe 1 and the thickness of the non-magnetic insulator N3. .

In addition, in the above embodiment, since the magnetoresistive film stripe 1 is formed by the deposition method in a switching orthogonal magnetic field, an increase in sensitivity can be obtained thereby, making it possible to obtain an element with extremely high sensitivity. .

〔Effect of the invention〕

As mentioned above, according to the present invention, since the magnetoresistive film stripe that requires the terminal to be drawn out can be exposed on the surface, the drawbacks of the prior art are eliminated, and there is no risk of complicating the manufacturing process. It is easy to provide a magnetoresistive element with high sensitivity and low cost.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the magnetoresistive element according to the present invention, FIG. 2 is an explanatory diagram of the basic element shape of the magnetoresistive element, and FIG. 3 is a conventional example of the magnetoresistive element. 4 is an explanatory diagram showing an example of a magnetic sensor using a magnetoresistive element, FIGS. 5(a) and (b) are explanatory diagrams of the reverse pattern, and FIG. 6 is a detailed diagram of the present invention. FIG. 7 is an explanatory diagram showing the relationship between the stripe and the thickness of the magnetic field focusing film. l... Magnetoresistive film stripe, 2.2'.
...Magnetic field focusing film, 3...Nonmagnetic insulating layer,
5... Board. Fig. 1 q::22 Sho Hχ Fig. 3 Ren=:zulv 5th prisoner (b) Fig. 6 Fig. 7

Claims (1)

[Scope of Claims] 1. Detection of ferromagnetic thin film stripes having magnetoresistive effect In a magnetoresistive element including a magnetic field focusing film made of strip-shaped high magnetic permeability magnetic material arranged adjacently in parallel along the magnetic field direction,
The magnetic field focusing film is formed on a substrate surface, and the ferromagnetic thin film stripe is formed on a nonmagnetic insulating layer provided on the substrate surface on which the magnetic field focusing film is formed, covering the magnetic field focusing film. A magnetoresistive element characterized by: 2. Claim 1 is characterized in that the thickness of the magnetic field focusing film is greater than or equal to the sum of the thickness of the ferromagnetic thin film stripe and the thickness of the nonmagnetic insulating layer. Magnetoresistive element. 3. The magnetoresistive element according to claim 1 or 2, wherein the ferromagnetic thin film stripe is composed of a nickel-cobalt alloy film or a nickel-cobalt-iron alloy film. 4. A magnetoresistive element according to any one of claims 1 to 3, characterized in that the ferromagnetic thin film stripe is formed by a deposition method in a switching orthogonal magnetic field.