JPH0442078A - Multi-operation type magnetoresistance element device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetoresistive element that detects the strength or change in magnetic field as a change in electrical resistance (sometimes simply referred to as resistance).

[Prior art] Magnetoresistive elements are used in various magnetic detectors and magnetic scales for detecting magnetic flux and magnetic field strength! Widely used in signal detection parts.

Magnetoresistive elements include semiconductor magnetoresistive elements whose electrical resistance changes as the xi path changes due to a magnetic field, and ferromagnetic magnetoresistive elements whose electrical resistance changes as the direction of magnetization changes due to a magnetic field. The magnetoresistive effect also differs depending on the type of semiconductor or ferromagnetic material. Therefore, the properties of magnetoresistive elements vary greatly depending on the material that constitutes the element.

For this reason, in magnetic detectors and the like, appropriate magnetoresistive elements are appropriately selected and used depending on the purpose of use.

In other words, conventional ferromagnetic magnetoresistive elements used in magnetic detectors and the like have a structure in which the element is formed of a material that has a specific magnetoresistive effect on a glass substrate, which is an insulator. , magnetic field detection becomes possible only under certain specific conditions.

For example, in a magnetoresistive element using a permalloy-based ferromagnetic material, resistance changes when there is a change in magnetic field or magnetic flux of several 10 to 1000 e.

Therefore, when using a permalloy magnetoresistive element, the magnetic field or magnetic flux needs to change by a corresponding amount on the memory side, that is, on the side that causes the magnetoresistive element to output a signal (magnetic field) (the side to be detected). There is. In other words, the signal processing mechanism only creates a single change in magnetic field on the detected side and converts it into an electrical signal using a magnetoresistive element (sensor).

[Problem to be solved by the invention]

The purpose of actually detecting changes in the magnetic field and obtaining signals is to detect the position of a moving body and convert it into the number of rotations. Therefore, it is desirable to be able to magnetically detect the reference position (origin) of a moving body or a rotating body.

However, by placing a magnet 12 behind the magnetoresistive element 10 as shown in FIG. When detecting, or when detecting a magnetized part 28 formed on a detected object 2o made of a ferromagnetic material 26 as shown in FIG. 6, a deep recess 22a or a strongly magnetized part 28a corresponding to the origin is detected.
Even if they exist, the change in resistance due to the magnetic field will reach saturation, making it impossible to distinguish between them.

That is, when detecting with a single magnetoresistive element with magnetoresistive effect characteristics, it is not possible to detect a wide range of changes in the magnetic field, and it is not possible to obtain multiple types of detection signals. It is conceivable to make the reference level of the comparator variable for detection, but it is difficult to detect multiple levels of magnetic fields when noise, gap fluctuations, etc. are taken into account.

On the other hand, in recent years, with the miniaturization and higher performance of various devices, it is necessary to process multiple signals at the same time, and there is an increasing demand for compact sensor bodies, and it is necessary to respond to these demands. .

The present invention has been made in order to eliminate the drawbacks of the prior art, and aims to provide a multi-operation type magnetoresistive element device that can easily and accurately detect changes in a magnetic field at multiple levels. .

[Means to solve the problem]

The magnetoresistive effect (change in electrical resistance with respect to change in magnetic field) of a magnetoresistive element has a relationship as shown in FIG. In other words, as the magnetic field strength increases, the electrical resistance changes, but when the magnetic field strength exceeds a certain value, the change in resistance becomes saturated. In this case, the curve A is shown in FIG. 8, and the electrical resistance changes up to about 1 to 10 kG @magnetic field. On the other hand, a magnetoresistive element made of a ferromagnetic material such as Fe-Nj, NiCo, etc. has a change in electrical resistance of several tens to several thousand e as shown in curve vAB.
Furthermore, by adding elements that increase magnetic anisotropy, such as rare earth elements, to a ferromagnetic thin film element, the characteristics of the magnetoresistive effect (relationship between resistance and magnetic field strength) can be changed. .

The present invention was made by focusing on the fact that the characteristics of the magnetoresistive effect differ greatly depending on the material forming the magnetoresistive element as described above, and the present invention is based on the magnetoresistive effect in which the electrical resistance changes depending on the strength of the magnetic field. It is characterized in that a plurality of magnetoresistive elements having different characteristics are provided on an insulating substrate.

The plurality of magnetoresistive elements may be stacked or may be arranged planarly on the substrate.

[Effect]

In the present invention configured as described above, by providing a plurality of magnetoresistive elements with different magnetoresistive effect characteristics, when there is a change in the magnetic field at multiple levels, the element that responds best to each level detects it. Therefore, changes in the magnetic field at multiple levels can be easily and accurately detected.Furthermore, since multiple elements are provided on the same substrate, multiple detection signals can be extracted at the same time. It is possible to downsize the sensor.

〔Example〕

A preferred embodiment of the multi-acting magnetoresistive element device of the present invention will be described in detail with reference to the accompanying drawings. Note that the same reference numerals are given to the parts corresponding to the parts explained in the prior art, and the explanation thereof will be omitted.

FIG. 1 is a cross-sectional view of a multi-acting magnetoresistive element device according to a first embodiment of the present invention.

In FIG. 1, a magnetoresistive element device 30 includes three layers of magnetoresistive elements 34, 36, and 38 having a magnetoresistive effect whose electrical resistance changes depending on the strength of a magnetic field on a Pyrex glass substrate 32, which is an insulator. It is laminated. These magnetoresistive elements 34, 36, and 38 are composed of a ferromagnetic thin film or a semiconductor thin film, and have different magnetoresistive characteristics. That is, each magnetoresistive element 34.3
6.38 have different response regions to magnetic field strength and changes. And each magnetoresistive element 34.36
．． Lead on 38! ! 40.42.44 are connected, and Pyrex glass 46.4 is connected between each element.
8 is interposed to provide insulation between the elements.

In the embodiment constructed as described above, each magnetoresistive element 334.3
6.38 outputs different detection signals, so
The strength of the magnetic field can be easily, reliably and accurately detected over a wide range, and differences in the level of changes in the magnetic field can be easily and reliably detected. For this reason,
The effect can be increased by combining with a bias magnetic field, such as detecting multiple pieces of information from a memory or detecting the intensity distribution of a magnetized pattern. Moreover, each magnetoresistive element 34.3
6.38 is laminated, the magnetoresistive element device 30 can be made extremely compact.

For example, a magnetoresistive element device 30 in which a magnetoresistive element made of a ferromagnetic material and a magnetoresistive element made of a semiconductor are laminated,
When detecting the magnetization of the detected object 20 shown in FIG. 6,
It will look like Figure 2. In other words, since the magnetoresistive element (MR) iL made of ferromagnetic material has high sensitivity and the change in resistance is saturated in a low magnetic field, as shown in FIG. 2(B), the weakly magnetized part 28 and the strongly magnetized part 28a The detection signals (outputs) of both will be the same. On the other hand, a semiconductor magnetoresistive element has a small output for the weakly magnetized portion 28 and a large output for the strongly magnetized portion 28a (FIG. 2(C)).

Of course, the difference can be increased by adjusting the magnitude and sensitivity of the magnetic field.

In this way, the detection range of the magnetic field is widened and the level of magnetization can be detected, so it is possible to display the origin on position sensors and linear scales, set digits by combining the magnetization pattern and embedded magnets, and the origin of rotation sensors. Settings, etc. are now possible.

Note that the Pyrex glass 46 of the magnetoresistive element device 30
．． It is desirable to make the magnetoresistive elements 48 as thin as possible in order to improve the characteristics of the magnetoresistive element device 30. However, care must be taken because if the magnetoresistive elements 34, 36, and 38 are too close together, they will affect each other. Further, in the above embodiment, the Pyrex glass 46.4 is used between the magnetoresistive elements.
In the above embodiment, a thin film insulating material such as SiO□ may be interposed between each magnetoresistive element. Niri 1D line 40.42.4 respectively
Although the case where four magnetoresistive elements are provided has been described, each magnetoresistive element may be connected in series, or more magnetoresistive elements may be stacked and any number of magnetoresistive elements may be connected in series.

FIG. 3 is an explanatory diagram of a magnetoresistive element device according to a second embodiment of the present invention.

In FIG. 3, the magnetoresistive element device 30 includes a ferromagnetic Fe-Ni thin film 50 and a Fe-Co-RE thin film 52 provided on a Pyrex glass substrate 32 in a planar manner. A conductive thin film 54 made of Ag or the like is provided between the two to electrically connect the ferromagnetic thin films 50 and 52. Also, each thin film 50.52.54
The part is cut out into a meandering band pattern 56 by laser processing or the like, and the Fe of this band pattern 56 is cut out by laser processing or the like.
The -Ni thin film 50 and the Fe-Co-RE thin film 52 form magnetoresistive elements with different magnetoresistive characteristics.

At both ends of the strip pattern 56, lead! ! 5B and 60 are provided, and a DC power source 62 is connected to the lead wires 58 and 60 so that a current can flow through the pattern 56. Furthermore, a detection lead wire 64 is attached to the middle part of the strip pattern 56.
By detecting the voltage between the lead wire 64 and the lead wire 58 or the lead wire 60, a detection signal due to a change in the magnetic field can be extracted.

Magnetoresistive element device 30 of the second embodiment configured in this way
When the magnetization of the object to be detected 20 shown in FIG. 2(A) is detected, the result is as shown in FIG. 4.

That is, in the conventional magnetoresistive element, there is not much difference in the magnitude of the detection signal between the weakly magnetized portion 28 and the strongly magnetized portion 28a (Fig. 4(C)), and it is difficult to distinguish the strength of magnetization. It was difficult.

On the other hand, in the embodiment, as shown in FIG. 4(B), there is a large difference in the detection signals for the weakly magnetized portion 28 and the strongly magnetized portion 28a, and it is difficult to clearly distinguish the difference in magnetization. be able to. That is, in the case of the embodiment, superimposed detection signals from two types of magnetoresistive elements are obtained, and a detection element is designed that has a comprehensive detection signal pattern characteristic that cannot be obtained with only one magnetoresistive material. I can do it. Therefore, the same effects as in the embodiment described above can be obtained.

In the second embodiment as well, a lead wire may be attached to each magnetoresistive element section to take out the output signal of each of the plurality of magnetoresistive elements. Of course, it is possible to combine the system and the semiconductor system. Furthermore, thin films of three or more types of magnetoresistive materials having different characteristics may be formed on the Pyrex glass substrate 32.

〔Effect of the invention〕

As explained above, according to the present invention, by providing a plurality of magnetoresistive elements with different magnetoresistive effect characteristics on the same substrate, when there is a change in the magnetic field at multiple levels, each level Since the element that responds best detects it, changes in the magnetic field at multiple levels can be detected with ease and accuracy. Moreover, since a plurality of elements are provided on the same substrate, it is possible to simultaneously extract a plurality of detection signals, and it is also possible to downsize the sensor.

[Brief explanation of the drawing]

1 is a sectional view of a magnetoresistive element device according to a first embodiment of the present invention, FIG. 2 is an explanatory diagram of the operation of the first embodiment, FIG. 3 is an explanatory diagram of the second embodiment, and FIG. 4 is an explanatory diagram of the operation of the first embodiment. 5 is a comparison diagram of the output signals of the second embodiment and the conventional example, and FIGS. 5 and 6 are examples of objects to be detected in which changes in the magnetic field are detected. Figure 6 is a cross-sectional view of a target to be detected with different magnetization strengths, Figure 7 is a diagram showing the relationship between the magnetic field and electrical resistance of a magnetoresistive element, and Figure 8 is a diagram of a semiconductor. FIG. 3 is a diagram showing the relationship between the magnetic field and electrical resistance of a magnetoresistive element and a ferromagnetic magnetoresistive element. 30-1---Magnetoresistive element device, 32--Pyrex glass substrate, 34.36.38 ・--1--Magnetoresistive element, 50 ~---- Fe-Ni-based thin film, 52- ---Fe-Co-RE thin film. Figure 1 Figure 2

Claims (3)

[Claims] (1) A multi-operation type magnetoresistive element device characterized in that a plurality of magnetoresistive elements having different magnetoresistive effect characteristics whose electrical resistance changes depending on the strength of a magnetic field are provided on an insulating substrate. (2) The multi-operation magnetoresistive element device according to claim 1, wherein the plurality of magnetoresistive elements are stacked. (3) The multi-operation magnetoresistive element device according to claim 1, wherein the plurality of magnetoresistive elements are arranged in a plane on the substrate.