JPH0444371A - Magnetoresistance device - Google Patents

Abstract

PURPOSE:To obtain a highly saturated magnetic field and a required resistance value by forming a plurality of a thin ferromagnetic film patterns which are slender in parallel and striped electrodes which are common to the plurality of thin ferromagnetic film patterns. CONSTITUTION:Thin ferromagnetic film patterns 20 are arranged to wind mean deringly. A slit 22 is provided on the pattern located in a region subject a high outside magnetic field, thereby producing a plurality of stripes of thin patterns which are parallel to the thin ferrofmagnetic film patterns 20. More over, electrodes 21, which comprise Au or the like striped on the slant, are installed on the surface of the thin ferromagnetic film patterns 20. The electrode patterns 21 are installed so that they may be common to the plurality of stripes of patterns which go in parallel. This construction eliminates a marked differ ence between the electric resistance of the thin ferromagnetic film patterns and that of a region subject to a weak outside magnetic field, thereby increasing the saturated magnetic field in a section where the thin ferromagnetic film patterns are made slender. It is, therefore, possible to extend the range of detec tion magnetic field and moreover obtain a required resistance value.

Description

[Detailed Description of the Invention] [Summary] Regarding a magnetoresistive element that detects a magnetic field, the barber-pole magnetoresistive element using a ferromagnetic thin film aims to have a high saturation magnetic field and obtain a desired resistance value. It is composed of a plurality of parallel elongated ferromagnetic thin film patterns and a striped electrode pattern formed in common to the plurality of ferromagnetic thin film patterns.

[Industrial application field]

The present invention relates to a magnetoresistive element that detects a magnetic field.

Magnetoresistive elements have high sensitivity, so they are used in combination with magnetic circuits in angle sensors, acceleration sensors, and the like. At that time, depending on various conditions such as the magnetic field range to be detected and noise resistance against disturbance magnetic fields, the saturation magnetic field, sensitivity,
Optimal values for resistance etc. are determined. Therefore, it is necessary to be able to design the above-mentioned characteristics as required.

[Conventional technology]

A conventional barber pole type magnetoresistive element is shown in FIG.

As shown in the figure, this consists of a resistor pattern 2 formed on a silicon substrate 1 on which an oxide film has been grown, and external connection elements 3 and 4.
．． 5 are integrally connected, and the resistor pattern 2 is a soft magnetic thin film 6 such as permalloy formed in a zigzag shape.
A conductive material (for example, gold) 7 is formed in a striped shape that is slanted. After initially magnetizing the resistor pattern 2 in its longitudinal direction, a predetermined current is applied between the terminals 3 and 4.5, and an external magnetic field He perpendicular to the length direction of the resistor pattern 2 is applied.
When x is applied, a change in resistance value occurs in the resistor pattern 2, and the presence or absence of an external magnetic field Hex can be detected from this change in resistance value.

FIG. 4 shows a conceptual diagram of an acceleration sensor using the above magnetoresistive element. As shown in the figure, on the substrate 10,
One end of a spring 12 having a permanent magnet 11 at its tip is supported and fixed, and two magnetic resistance elements 13a are placed near the permanent magnet 11.
, 13b are arranged. And when acceleration is added,
The spring 12 bends and the permanent magnet 11 swings. This deflection of the permanent magnet 11 causes a change in the magnetic field in the magnetoresistive elements 13a, 13b, and the magnetoresistive elements output an output corresponding to the change in the magnetic field strength.

In such an acceleration sensor, since the distance between the permanent magnet 11 and the magnetoresistive elements 13a and 13b is small, the magnetic field from the permanent magnet 11 is not uniform within the magnetoresistive element chip. However, in the conventional magnetoresistive element, the width of the ferromagnetic thin film pattern 6 is the same everywhere on the chip as shown in FIG. 3, so the sensitivity and saturation magnetic field characteristics are uniform within the chip. That's the part where the magnetic field strength from the permanent magnet 11 is strong (the part near the permanent magnet 11 of the magnetoresistive elements 13a and 13b)
Actually, a magnetic field higher than the saturation magnetic field is applied, and even if there is a displacement of the permanent magnet 11, that is, a change in the magnetic field, there are cases where no output is produced at all.

On the contrary, the magnetic field strength is weak in the part far from the permanent magnet 11, and the output is small.

For this reason, as shown in FIG. 5, it has been proposed that the ferromagnetic thin film pattern 6a in the region where the magnetic field is strong has a narrower pattern width than the region where the magnetic field is weaker so that the saturation magnetic field becomes higher. (Patent Application No. 2-61629) [Problems to be Solved by the Invention] In conventional magnetoresistive elements, in order to increase the saturation magnetic field, it is necessary to reduce the thickness of the ferromagnetic thin film or narrow the pattern width. I was dealing with this.

On the other hand, the ferromagnetic thin film pattern 6 for detecting a non-uniform magnetic field, such as the magnetoresistive element for an acceleration sensor shown in FIG. 5, has a pattern width that differs between a strong magnetic field range and a weak magnetic field range. However, in this case, although the sensitivity and saturation magnetic field of the element differ in parts with different pattern widths, since the patterns have the same thickness, the resistance value differs depending on the pattern width, and when looking at the entire magnetoresistive element, the pattern width There was a problem in that the ratio of resistance at the thinnest portion of the wire was increased.

SUMMARY OF THE INVENTION In view of the above conventional problems, an object of the present invention is to provide a magnetoresistive element that has a high saturation magnetic field and can obtain a desired resistance value.

[Means to solve the problem]

In order to achieve the above object, in the magnetoresistive element of the present invention, in a barber pole magnetoresistive element using a ferromagnetic thin film, a plurality of parallel elongated ferromagnetic thin film patterns 20
and a striped electrode pattern 21 formed in common to the plurality of ferromagnetic thin film patterns 20.

[For production]

In the magnetoresistive element of the present invention, as shown in the principle explanatory diagram of FIG. 1, the width of the ferromagnetic thin film pattern 20 is extremely small, and the electrode pattern 21 arranges a plurality of ferromagnetic thin film patterns 20 in parallel. If arranged in this way, the saturation magnetic field will be high (the detected magnetic field range will be wide) and the desired resistance value will be obtained.

〔Example〕

FIG. 2 is a diagram showing an embodiment of the present invention. In the figure, 20 is a ferromagnetic thin film pattern, and 21 is an electrode pattern.

In this embodiment, as shown in the figure, a ferromagnetic thin film pattern 20
The ferromagnetic thin film pattern 20 is made into a zigzag shape, and slits 22 are inserted in the region where the external magnetic field is strong, so that the ferromagnetic thin film pattern 20 has a plurality of parallel thin strips, and slits are inserted in the region where the external magnetic field is weak. The pattern width is kept wide, and furthermore, an oblique striped electrode pattern 21 made of Au or the like is provided on the ferromagnetic thin film pattern 20. This electrode pattern 21 is provided in common to a plurality of parallel patterns in the portion where the pattern width of the ferromagnetic thin film pattern 20 is narrowed.

In this embodiment configured in this way, the width of the ferromagnetic thin film pattern 200 is narrow in areas where the external magnetic field is strong, but the electrode pattern 21 is arranged so that a plurality of ferromagnetic thin film patterns are arranged in parallel. As a result, the electrical resistance of the ferromagnetic thin film pattern in this area is not much different from that in the area where the external magnetic field is weak. Furthermore, the saturation magnetic field becomes higher in the thinner part of the ferromagnetic thin film pattern. Therefore, the detection magnetic field range becomes wider,
Moreover, a desired resistance value can be obtained.

〔Effect of the invention〕

As explained above, according to the present invention, a ferromagnetic thin film pattern in a region with a strong external magnetic field is divided into a plurality of narrow pattern width patterns, and a common electrode pattern is provided to the plurality of patterns, whereby the core Since the saturation magnetic field of the magnetic field can be increased and the desired resistance value can be obtained, changes in the magnetic field can be detected without magnetic saturation even if the external magnetic field is non-uniform, and high performance can be achieved. can.

[Brief explanation of drawings]

Fig. 1 is a diagram illustrating the principle of the present invention, Fig. 2 is a diagram showing an embodiment of the present invention, Fig. 3 is a diagram showing a conventional barber pole type magnetoresistive element, and Fig. 4 is a diagram showing a conventional barber pole type magnetoresistive element. A conceptual diagram showing an acceleration sensor. FIG. 5 is a diagram showing a magnetoresistive element for detecting a non-uniform magnetic field. In the figure, 20 indicates a ferromagnetic thin film pattern, and 21 indicates an electrode pattern. 20...Ferromagnetic thin film pattern 21...Electrode pattern No. 1 Fig. 3 Diagram showing an embodiment of the present invention Fig. 2 20...Ferromagnetic thin film pattern 21...・Electrode pattern 22...Fourth conceptual diagram showing a slit sensor

Claims (1)

[Claims] 1. In a barber pole type magnetoresistive element using a ferromagnetic thin film, a plurality of parallel elongated ferromagnetic thin film patterns 20 and a plurality of ferromagnetic thin film patterns 20 formed in common to each other. A magnetoresistive element characterized by comprising a striped electrode pattern 21.