JPS62259486A - Magnetic sensor - Google Patents

Abstract

PURPOSE:To eliminate accuracy of size and realizes reduction in insize by matching the magnetizing direction to the target direciton with the striped magnetic film used as the bias stripe. CONSTITUTION:After forming a ferromagnetic thin film such as Ni-Co, Ni-Fe, etc. on a chip substrate 1 formed by glass, alumina, ferrite, etc., a desired sensor element 2 is formed. Next, a thin film electric insulation layer 3 such as SiO2, Ai2O3 is stacked thereon to form a thin film 4 having a high anti-magnetic force such as Co-P, ferrite. This thin film layer 4 is molded to a bias stripe 5 and thereafter the bias stripe 5 is then magnetized in the target direction (generally, in the width direction of the bias stripe 5) and the bias stripe 5 is given residual magnetism. With such residual magnetism, bias magnetic field can be applied to the sensor element 2.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic sensor, and more particularly to an r 7+ M R sensor that detects a signal magnetic field by varying magnetic resistance.

One of the conventional magnetic sensors is the SIR sensor, which detects changes in the magnetic field by changes in the magnetic resistance of the detection sea lion constituting the sensor, and is widely used because it is small and lightweight and has good sensitivity. However, if the MR sensor is used in an unbiased state (heavily used), the detection output waveform will be distorted due to the magnetic properties of the sensor itself such as hysteresis characteristics, and noise will be generated, causing weak signals to be distorted. 4. No. 57 is a bottom view showing the structure of a Si RJ sensor without magnetic bias according to the prior art. A sensor element is formed by a ferromagnetic thin film on a chip substrate 11.
12f; and electrodes 13, 14.15 connected thereto are formed, and a line 1.1. A DC voltage of 1 G is applied through No. 3. When the positive and negative directions of the DC voltage are in the directions shown in Figure 5, the central electrode 1t and the Ti at the ends
Signal output corresponding to external magnetic field between poles 15■out is line! 2. e,1.

FIG. 6 is a graph showing the magnetic characteristics when the MR sensor is used in a non-biased state. In the graph, the vertical axis shows the rate of change in magnetoresistance (%) of the sensor, and the horizontal axis shows the change in the external magnetic field (〃us) corresponding to the sensor. As mentioned above, when the MR sensor is used in an unbiased state, the hysteresis characteristic causes the magnetoresistive rate to have a bimodal state indicated by the arrow a, and the resulting output waveform is distorted and inaccurate. Become something. Also, the park indicated by the arrow mark~
Noise due to the Uzen effect 1 and noise shown by arrow C due to magnetization rotation are generated, and both of these are harmful to accurate magnetic detection, especially detection of weak signal magnetic fields.

7th (2I) is a waveform diagram showing the (i) output waveform when the MR sensor is used in a non-biased state.The waveform diagram shows the output (V) on the vertical axis and the phase (degrees) on the horizontal axis. ing.

Since the sensor has no bias, the output waveform obtained is a vertically asymmetric distorted waveform, and as described above, the waveform contains noise components.

In this way, it is not preferable to use the >i R sensor in an unbiased state, and for this reason, in the prior art, various ideas have been made to bias the \IR sensor.

Figures 8 to 10 are diagrams showing the magnetic bias method of the hi R sensor according to the prior art. FIG. 3 is a perspective view illustrating a method of attaching the sensor element 23 so as to be perpendicular to the magnetization direction as shown in d, thereby controlling the magnetic bias. In FIG. 9, a conductor 24 is arranged above and close to the sensor element 23, and this conductor 2
4 is a sectional view illustrating a method of generating a magnetic field indicated by an arrow e through an electric current, thereby applying a magnetic bias. Further, FIG. 10 is a sectional view similar to FIG. 9, showing a method in which a stripe 25 made of a permanent magnet is disposed close to above the sensor element 23, and a magnetic bias is applied by a magnetic field indicated by an arrow f. It is.

However, these conventional magnetic bias methods
For example, in the method using a single permanent magnet 22 shown in FIG. 8, in order to uniformly apply a magnetic bias to the entire sensor element 23, the thickness of the sensor element 23 must be several times as large as 1! The current biasing method shown in FIG. 9, which requires a permanent magnet 22 with a length of 'f, naturally requires a bias current source and increases power requirements. Furthermore, the method using the stripe magnet 25 shown in FIG.
In addition to the difficulty of manufacturing 5, this stripe magnet 2
5 had to be formed overlappingly above the sensor element 23. However, the above-mentioned conventional magnetic bias methods are subject to size constraints, which results in the result of reducing the advantage of small size and light weight that the MR sensor itself has. Therefore, there has been a desire for a magnetic bias method that improves the electrical performance without diminishing the geometrical advantages of the MR sensor itself.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned technical problems and to provide a magnetic sensor with a simple structure and easy manufacture.

Means for Solving the Problems The present invention forms on a chip substrate a quasi-number or multiple rows of sensor elements that change their magnetic resistance in response to an external magnetic field, and the sensor elements are made of ferromagnetic material in a striped pattern. A thin film electrically insulating layer is laminated above the sensor element, and multiple rows of stripes made of antimagnetic material are melted through the thin film electrically insulating layer to be perpendicular to the sensor element or obliquely at an arbitrary angle. This magnetic sensor is characterized in that it is formed on an electrically insulating layer, and the stripe is magnetized in a target direction to add residual magnetism to provide a magnetic bias to the sensor element.

According to the present invention, a striped magnetic film is formed on a magnetic sensor element via a thin film electrical insulating layer, and the magnetization direction can be made to coincide with the target direction. To realize a stable magnetic bias method without increasing the shape.

Embodiment FIG. 1 is a plan view of an embodiment of the present invention, and FIG. 2 is a plan view of an embodiment of the present invention.
52 is a sectional view taken along the photopic plane line Δ-A in FIG. 51. FIG. The manufacturing method will be explained below with reference to FIGS. 1 and 2.

Ni—Co is deposited on a chip substrate 1 made of positive, alumina, 7-elite, etc. by vapor deposition.

Ferromagnetic material such as Ni-Fc? After forming the i-film, a desired sensor element 2 is formed by photoetching. Next, T of SiO2, A i, 03, etc.? The I-type electric insulating layer 3 is laminated, and T? After forming the i-film layer 4 into a desired bias stripe 5 by photo-etching, the bias stripe 5 is magnetized in the desired direction (generally one width direction of the bias stripe 5). Adds residual magnetism to This residual magnetism makes it possible to apply a bias magnet m to the sensor element 2.

In addition, in Fig. 1, the sensor element 2 is illuminated and the bias stripes 5 are orthogonal to each other, and when a bias is applied in such an important direction, a signal output waveform with a frequency twice that of the external alternating magnetic field is obtained. It will be done.

FIG. 3 is a plan view showing another embodiment of the invention. Third
The figure is similar to the previously described embodiment, and corresponding parts are provided with the same reference numerals. The point of interest in this embodiment is that the bias stripe 5 is diagonally arranged with respect to the sensor element 2, and in this embodiment, the bias stripe 5 is diagonally crossed at an angle of 45°. In this case, when the bias stripes 5 and the sensor element 2 are crossed at a right angle, a signal output waveform equal to the frequency of the external alternating magnetic field is obtained. Although it was shown in two examples at 45°,
It is not limited to this, and may be formed at any other arbitrary angle. As mentioned above, the angle can be arbitrarily designed when creating a photomask during photoetching.

The m4 diagram shows the MR with magnetic bias added according to this embodiment.
1 is a waveform diagram of the signal output of the sensor.1 It can be seen that the output waveform is dramatically improved by the magnetic bias method according to the present invention compared to the signal output waveform in the non-biased state shown in FIG.

Effects As described above, according to the present invention, a striped magnetic film is formed on a magnetic sensor element via a thin electrical insulating layer, and this striped magnetic film is used as a bias stripe to determine the direction of magnetization. Moreover, since the bias stripe is formed widely relative to the sensor element group, dimensional accuracy is not required, and the shape is compact, so it saves space when used in various devices. 1. The magnetic bias method according to the present invention alters the magnetic characteristics of the sensor itself, and improves the signal output I1. Of course, the shape can be obtained.

[Brief explanation of drawings]

FIG. 1 is a plan view of an embodiment of the present invention, FIG. 2 is a sectional view thereof, FIG. 3 is a plan view of an embodiment of the pond of the present invention, and FIG. 4 is a waveform of a signal output obtained by the present invention. Figure 5 is a plan view showing the prior art, Figure 6 is a graph showing the characteristics of the magnetic sensor according to the prior art, Figure 7 is a waveform diagram of the Ibo output according to the prior art, and Figures 8 to 10 are FIG. 2 is a diagram for explaining a magnetic bias method according to the prior art. 1.11.21... Chimbu board, 2.12.23...
Sensor element, 3... thin film TL insulating layer, t.
...Thin film layer, 5...Bias stripe, G, i3,1
4.15...electrode, 7...conductor agent, patent attorney Keiichi Nishikyo - No change in the contents of the surface separation) Figure 1, Figure 3, iforo (false), Figure 5, external sound tλt! Ascend! , 2 (first time)
/ Igbo 1 non-g (splaining) Fig. 6 Fig. 7
Figure 2 Figure 8 Figure 10 Procedural Amendment 78 (Method) April 1, 1985

Claims (1)

[Scope of Claims] Single or multiple rows of sensor elements that change their magnetic resistance in response to an external magnetic field are formed on a chip substrate, and the sensor elements are formed into striped thin films of ferromagnetic material. laminating a thin film electrically insulating layer above the element, forming multiple rows of stripes made of antimagnetic material orthogonal to the sensor element or diagonally at an arbitrary angle on the thin film electrically insulating layer through the thin film electrically insulating layer; A magnetic sensor characterized in that the stripe is magnetized in a target direction to add residual magnetism to provide a magnetic bias to the sensor element.