JP2769403B2 - Magnetoresistive element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive element utilizing a magnetoresistive effect of a magnetically sensitive thin film formed of a ferromagnetic metal.

[0002]

2. Description of the Related Art Conventionally, magnetic sensors have been widely used as proximity switches, position detectors, electronic lock devices, keyboards, thin-film magnetic heads, pressure switching sensors, pattern recognition sensors, and the like. As a magnetic sensor for measuring the intensity of a magnetic field, a magnetoresistive element having a magnetoresistive effect is widely used.

[0003] Here, the magnetoresistance effect refers to a phenomenon in which when an element such as a semiconductor is placed in a magnetic field, the electric resistance of the semiconductor or the like changes. This is because the path of the carrier moving in the solid is bent by the electromagnetic force, and the current path changes. As a magnetoresistive element utilizing the magnetoresistive effect, a device utilizing a compound semiconductor such as indium antimony and gallium arsenide and a magnetic sensitive thin film formed of a ferromagnetic metal such as Ni, Ni-Co, permalloy are utilized. Two types are used.

Generally, when a magnetic field is applied to a semiconductor magnetoresistive element, its internal resistance increases. That is, the semiconductor magnetoresistive element has positive magnetic characteristics. In contrast, when a magnetic field is applied to a ferromagnetic magnetoresistive element, its internal resistance decreases. That is, the ferromagnetic magnetoresistive element has negative magnetic characteristics.

On the other hand, conventionally, a magnetically responsive thin film formed of a ferromagnetic metal is formed by depositing a thin film having a thickness of about 1000 angstroms on a glass substrate using a vacuum deposition method or a sputtering method using a permalloy or the like. Is formed.
Here, the quality of the formed magnetically responsive thin film was controlled by the temperature of the crucible for evaporating the ferromagnetic metal, the degree of vacuum, the heating temperature of the glass substrate, the deposition rate, and the like.

Here, as the quality of the magnetically responsive thin film, it is desired that the rate of change in magnetoresistance, which changes in accordance with the strength of the magnetic field, is high and that the hysteresis indicating the magnitude of the remanence is small. Here, it is desirable that the hysteresis be small, when the magnetic field changes or disappears.
This is to always accurately measure the magnetic field without adversely affecting the next measured value. Therefore, in order to produce a magnetically responsive thin film having a higher magnetoresistance ratio and a smaller hysteresis than before, the crucible temperature, vacuum degree, glass substrate heating temperature,
Conditions such as the deposition rate were confirmed by experiments, and were controlled as manufacturing conditions.

[0007]

However, when the quality of the magnetically responsive thin film is controlled by the crucible temperature, the degree of vacuum, the glass substrate heating temperature, the deposition rate, etc., which are the production conditions in the production process by the vacuum deposition method as in the prior art. In, for example, when the vacuum evaporation apparatus or the like is changed, it is necessary to determine the optimum conditions by a new experiment.
Further, even when the apparatus itself is not changed, it is necessary to determine a plurality of conditions by experiments when the composition of the ferromagnetic metal is changed.

These experiments require a considerable number of experiments and are extremely complicated because there are a plurality of factors that affect the quality of the magnetoresistive element. Therefore, it has been difficult to stably manufacture a magnetoresistive element having a high magnetoresistance ratio and a small hysteresis.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a magnetoresistive element having a high magnetoresistance change rate and a small hysteresis easily and stably.

[0010]

In order to achieve this object, a magnetoresistive element according to the present invention is a magnetoresistive element utilizing a magnetoresistive effect of a magnetically sensitive thin film formed of a ferromagnetic metal, The average particle size of the ferromagnetic metal crystal constituting the magnetically responsive thin film is set to 50 to 150 angstroms.

[0011]

The magnetoresistive element of the present invention having the above-described structure has the following features.
When placed in a magnetic field, the electrical resistance decreases according to the strength of the magnetic field. The change in the resistance value is measured and converted into the strength of the magnetic field to measure the strength of the magnetic field. Since the average grain size of the crystal of the ferromagnetic metal constituting the magnetosensitive thin film of the magnetoresistive element of the present invention is controlled to 50 to 150 angstroms, the magnetoresistive film has a high magnetoresistance. Further, when the magnetic field changes or disappears, the hysteresis is smaller than that of the conventional magnetoresistive element, so that the next measured value is not adversely affected, and the magnetic field can always be measured accurately.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A magnetoresistive element according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration of a magnetic sensor 6 using the magnetoresistive elements 1 and 2. The magnetic sensor 6 is generally composed of a plurality of magneto-resistive elements. The reason is that when a single magnetoresistive element is used, the temperature dependence of the magnetoresistive element is large,
This is because a plurality of magnetoresistive elements are provided on the same substrate to perform temperature compensation differentially.

The same magnetoresistive elements 1 and 2 each have about 10
It is formed as a pattern having a line width of ２０20 μm. The patterns of the magnetoresistive elements 1 and 2 are formed so as to have a quadrature phase difference. The magnetoresistive elements 1 and 2 have a property that their resistance decreases when they receive a magnetic field at right angles to the longitudinal direction of the pattern lines. , The resistance value does not change.

Therefore, when a magnetic field A is applied in the longitudinal direction of the pattern line of the magnetoresistive element 1, the resistance value of the magnetoresistive element 2 decreases, but the resistance value of the magnetoresistive element 1 is
Does not change. Therefore, a change in the resistance value of the magnetoresistive element 1 directly represents a change in temperature, and temperature compensation is performed using this change. By taking the change in the resistance value into an arithmetic processor (not shown) from the terminals 3, 4, and 5, and performing arithmetic processing, the intensity of the temperature-compensated magnetic field A can be measured.

Next, a magnetically responsive thin film formed of a ferromagnetic metal, which is a main part of the present invention, will be described with reference to FIG. In this embodiment, permalloy (Ni-Fe, 83:17) is used as the ferromagnetic metal.

FIG. 2 is a diagram in which crystal grains are traced based on a photograph of the internal crystal structure of the magnetically sensitive thin film taken at a magnification of 200,000. The length of the diagonal H of the square in FIG.
Painted at 3535 angstroms. The number of crystal grains crossed by the diagonal line is (a) 18 and (b) 2
5 and (c) are 38.

Here, the average particle diameter R is defined as a number obtained by dividing the length of 3535 angstroms by the number of crystal grains crossed by the diagonal H. According to this definition, (a) is 19
6.4 Å, (b) becomes 141.4 Å, and (c) becomes 93.0 Å.

In this way, the average grain size R of the crystal is calculated, and the hysteresis iHc
(Unit Oersted; Oe) and the magnetoresistance ratio T
(Unit;%) was determined by experiment. FIG. 4, FIG. 5, FIG.
FIG. 2 is a data diagram showing the measured hysteresis of the magnetoresistive element having the respective average particle diameters shown in FIGS. 2 (a), (b) and (c). Here, in FIGS. 4, 5 and 6, W1, W2, W
3 represents the magnitude of the hysteresis, which is the remaining magnetism.

That is, when the average grain size R of the crystal is about 200 angstroms, the hysteresis is about 20 Oe. When the average grain size R of the crystal is about 140 angstroms, the hysteresis is about 3 Oe. R
Is about 90 angstroms, the hysteresis is about 2
Oe. Thus, the hysteresis iHc and the magnetoresistance ratio T obtained by the experiment and the average grain size R of the crystal are obtained.
Is shown in FIG.

As shown in FIG. 3, the magnetoresistance change rate T is
When the average grain size R of the crystal increases sharply up to 50 angstroms, and when the average grain size R of the crystal exceeds 50 angstroms, the rate of increase extremely decreases. On the other hand, the hysteresis H gradually increases when the average grain size R of the crystal is from 0 to 150 Å, and rapidly increases when the average grain size R of the crystal exceeds 150 Å.

From the experimental results, it was found that the average grain size of the crystals was 50
If the temperature is maintained at about 150 Å, a magnetoresistance element having a high magnetoresistance change rate T and a small hysteresis iHc can be manufactured. Therefore, a high-performance magnetoresistive element can be obtained by controlling the average particle diameter by a microscopic photograph of the crystal, instead of indirectly controlling the heating temperature of the glass substrate or the like as in the related art. Even if is changed, only the average grain size of the crystal of the magnetoresistive element needs to be managed, so that optimum manufacturing conditions can be easily found.

In the present embodiment, the number of crystals whose diagonal lines of 3535 angstroms intersect is used as a method for calculating the average grain size of the crystals. However, the present invention is not limited to this length, and various lengths may be used. Just set it.

[0023]

As is apparent from the above description, according to the magnetoresistive element of the present invention, the average grain size of the ferromagnetic metal crystal constituting the magnetically responsive thin film is set to be 50 to 150 Å. For example, even if the vacuum evaporation apparatus is changed, since only the average grain size of the crystal of the magnetoresistive element needs to be managed, it is possible to easily find the optimal manufacturing conditions, A magnetoresistive element having a high magnetoresistance ratio and a small hysteresis can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a magnetic sensor using a magnetoresistive element according to one embodiment of the present invention.

FIG. 2 is a trace diagram obtained by tracing a micrograph of a magnetoresistive element according to one embodiment of the present invention.

FIG. 3 is a data diagram showing the relationship between the performance of a magnetoresistive element and the average crystal grain size.

FIG. 4 is a data diagram showing a relationship between a magnetic field strength and a magnetization strength of a magnetoresistive element having an average crystal grain size of about 200 Å.

FIG. 5 is a data diagram showing a relationship between a magnetic field strength and a magnetization strength of a magnetoresistive element having an average crystal grain size of about 140 Å.

FIG. 6 is a data diagram showing a relationship between a magnetic field strength and a magnetization strength of a magnetoresistive element having an average crystal grain size of about 90 Å.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 magnetic resistance element 2 magnetic resistance element 6 magnetic sensor iHc hysteresis R average particle size of crystal T magnetoresistance change rate

Claims (1)

(57) [Claims] 1. A nickel 8 3%, nickel of iron 1 7% - magnetoresistance elements utilizing the magnetoresistance effect of the magnetic sensitive thin film formed by an iron alloy, the ferromagnetic constituting the magnetically sensitive film A micrograph of the body metal crystal is taken at a predetermined magnification, and a diagonal line having a length of H is drawn on the micrograph to calculate the number K of crystals at which the diagonal line intersects. When defined, the average particle diameter R is set to 50 angstrom or more to reduce the rate of increase in the magnetoresistance change rate of the magnetoresistive element. A magnetoresistive element, wherein the hysteresis of the resistive element is not more than 5 Oe.