JPH04273486A - Magnetoresistance element and adjustment method for mid-point voltage thereof - Google Patents

Abstract

PURPOSE:To adjust a mid-point voltage of a magnetoresistance element. CONSTITUTION:A magnetic resistance element is formed by connecting a plurality of stripes which consist of a ferromagnetic thin film having magnetoresistance effect in a bridge by four resistance elements 1, 3, 5, 6 which are constituted by folding a number of times approximately in parallel and two resistance elements 2, 4 which are constituted of a stripe pattern on the same insulating substrate 11. When a mid-point voltage of a bridge of the magnetoresistance element is adjusted, the stripe pattern of the two resistance elements is cut and the mid-point voltage of the bridge is adjusted.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive element used for detecting magnetic signals and a method for adjusting the midpoint voltage of the magnetoresistive element.

0002

2. Description of the Related Art A magnetoresistive element has stripes made of a ferromagnetic thin film having a magnetoresistive effect, and is used for detecting magnetic signals. An example of such a magnetoresistive element is shown in FIG.

[0003] This magnetoresistive element, as shown in FIG.
Consists of a ferromagnetic thin film. It has a structure in which resistive elements 51A, 51B, 51C, and 51D of the same shape are formed on an insulating substrate 52 and are folded back so that the stripes (longitudinal pattern) are almost parallel, and are connected to a bridge. . Magnetoresistive elements 51A, 51B, 51C, 5
A change in the midpoint voltage caused by a 1D difference in resistance change rate is detected as a change in magnetic field strength.

Generally, a magnetoresistive element for such use is shown in FIG.
A bridge circuit 61 of magnetoresistive elements is configured as shown in FIG. A method of amplifying and detecting the output signal via the differential amplifier circuit 62 is often used.

[0005]

In the conventional magnetoresistive element described above, as shown in FIG. 5, the resistance value of each of the four resistance elements is designed to be the same.
The midpoint voltage of input terminals 62A and 62B is 0V when there is no magnetic field.
Ideally, this is the case. However, it is difficult to make the four resistance elements manufactured by a thin film photolithography process made of a ferromagnetic thin film have the same resistance value, and there is a drawback that the midpoint voltage varies.

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetoresistive element and a method for adjusting the midpoint voltage thereof, which eliminates such drawbacks and makes it possible to adjust the midpoint voltage.

[0007]

[Means for Solving the Problems] The present invention provides a first resistor in which first stripes of a ferromagnetic thin film having a magnetoresistive effect are arranged substantially in parallel, and each first stripe is connected in series. In a magnetoresistive element formed in the shape of a bridge using four elements on the same insulating substrate, second stripes of a ferromagnetic thin film having a magnetoresistive effect are arranged almost in parallel, and each second stripe is It is characterized in that a second resistance element having stripes connected in parallel is connected in series to at least one first resistance element.

A method for adjusting the midpoint voltage of a magnetoresistive element bridge according to the present invention described above, in which a part of the stripe of the second resistance element is cut, and the magnetoresistive element is The midpoint voltage of the bridge is adjusted.

[0009]

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

FIG. 1 is a plan view showing an example of a magnetoresistive element according to the present invention. In the magnetoresistive element shown in FIG. 1, a ferromagnetic thin film is formed on an insulating substrate 11, and a plurality of stripes are connected in parallel to a resistance element 1 which is folded back using photolithography technology so that the stripes become parallel. The resistive elements 2 are connected in series. Further, it has a bridge structure including a resistance element 3 having folded stripes, a resistance element 4 having stripes connected in parallel, and resistance elements 5 and 6 having folded stripes.

Further, the electrode pad 7 is provided at the connection portion between the resistance element 2 and the resistance element 6. Similarly, the electrode pad 8 is provided at the connection portion between the resistance element 3 and the resistance element 4, the electrode pad 9 is provided at the connection portion between the resistance element 5 and the resistance element 6, and the electrode pad 10 is provided at the connection portion between the resistance element 5 and the resistance element 6. Element 6
and the resistance element 7.

Furthermore, the longitudinal direction of the resistance element 1 is perpendicular to the longitudinal direction of the resistance element 3 and the longitudinal direction of the resistance element 6. The longitudinal direction of the resistance element 2 is parallel to the longitudinal direction of the resistance element 1. The longitudinal direction of the resistance element 5 is perpendicular to the longitudinal direction of the resistance element 3 and the longitudinal direction of the resistance element 6. The longitudinal direction of the resistance element 4 is parallel to the longitudinal direction of the resistance element 5.

The equivalent circuit of such a magnetoresistive element is shown in FIG.
is shown. As shown in FIG. 2, magnetoresistive element 1, magnetoresistive element 2, magnetoresistive element 3, magnetoresistive element 4, magnetoresistive element 5, and magnetoresistive element 6 form a bridge.

Next, a method for adjusting the midpoint voltage of the magnetoresistive element shown in FIG. 1 will be explained. When adjusting the midpoint voltage of the magnetoresistive element, a power supply 21 is applied between electrode pads 9 and 10 on a magnetoresistive chip manufactured using photolithography, and a voltmeter 22 is applied between electrode pads 7 and 7. and 8. In order to adjust the midpoint voltage to 0V when there is no magnetic field, the resistance elements 2 and 4 are adjusted. This adjustment method is shown in FIG.

As shown in FIG. 3, a power supply 21 is applied to the magnetoresistive element, so that the voltmeter 22 indicates 0V.
If this is not the case, the laser 31 cuts, for example, the stripes of the resistive element 2 . In addition, if necessary, the stripes of the resistive element 4 are also cut. In this way, part of the stripe of the resistance elements 2 and 4 is cut with a laser, and the midpoint voltage of the bridge of the magnetoresistive element is adjusted to 0V. Figure 4
An example of a magnetoresistive element chip manufactured in this manner is shown in FIG. This example shows a pattern in which the resistive elements 2 and 4 are partially cut.

As described above, the magnetoresistive element of this embodiment has a structure in which a plurality of stripes made of a ferromagnetic thin film are folded many times so that each stripe becomes substantially parallel.
In a magneto-resistance element formed on the same insulating substrate so as to be connected to a bridge, two resistance elements each consisting of one resistance element and two resistance elements consisting of a plurality of stripes are formed on the same insulating substrate. A part of the stripe pattern is cut and the midpoint voltage of the bridge of the magnetoresistive element is adjusted.

[0017]

As explained above, the present invention has a resistor element having a structure in which a plurality of stripes made of a ferromagnetic thin film are folded many times so that each stripe is substantially parallel, and a plurality of parallel A magnetoresistive element chip manufactured by photolithography and bridge-connected with a resistance element made up of connected stripe patterns is later connected to two resistance elements made up of a plurality of striped patterns connected in parallel. Since the midpoint voltage of the magnetoresistive element can be adjusted by cutting a portion with a laser, for example, it is possible to create a magnetic detection circuit with less variation in characteristics.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an example of a magnetoresistive element according to the present invention.

FIG. 2 is a diagram showing an equivalent circuit and a detection circuit of the magnetoresistive element in FIG. 1;

FIG. 3 is a diagram showing a method for adjusting the midpoint voltage of the magnetoresistive element shown in FIG. 1;

FIG. 4 is a diagram showing an example of a magnetoresistive element manufactured by the method shown in FIG. 3;

FIG. 5 is a plan view showing an example of a conventional magnetoresistive element.

6 is a diagram showing an equivalent circuit and a detection circuit of the magnetoresistive element of FIG. 5. FIG.

[Explanation of symbols]

1 to 7 Resistance element 7-10 Electrode pad 11 Insulating substrate

Claims (2)

[Claims] Claim 1: A first ferromagnetic thin film having a magnetoresistive effect.
In a magnetoresistive element formed in the shape of a bridge by using four first resistance elements on the same insulating substrate, in which stripes are arranged almost parallel and each first stripe is connected in series, the magnetoresistive effect is A second resistive element in which second stripes of a ferromagnetic thin film having a ferromagnetic thin film are arranged substantially in parallel and each second stripe is connected in parallel is provided with at least one
A magnetoresistive element, characterized in that it is connected in series to a first resistance element. 2. A method for adjusting the midpoint voltage of a magnetoresistive element according to claim 1, which comprises: cutting a part of the stripe of the second resistance element; A method for adjusting a midpoint voltage of a magnetoresistive element, characterized in that the midpoint voltage of a bridge of the resistive element is adjusted.