JPS63314413A - Magnetic sensor and manufacture thereof - Google Patents

Abstract

PURPOSE:To enable detection and control of a position at a very high accuracy, by forming magnetic anisotropy of a magnetoresistance effect element (MR element) diametrically as opposed to a rotor magnetized circumferentially. CONSTITUTION:When an MR film 12 is formed on a substrate 1, a magnetic field generation source 5 is set on the back of the substrate 1 to generate a magnetic field diametrically in a radial manner. According to this method, a radial magnetic anisotropy is formed diametrically without being affected by a magnetic anisotropy as formed by incident and geometric effect during the formation of the film. Then, a pattern of a zigzag-shaped MR element 2 is formed by etching technique. When utilized for a surface opposed type sensor, this achieves a remarkably higher performance, thereby enabling detection and control of a position at a very high accuracy.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a magnetic sensor and a method for manufacturing the same, particularly a magnetic sensor in which a magnetoresistive element is arranged in a radial direction facing a circumferentially magnetized rotor. Related to sensors and their manufacturing method.

[Conventional technology]

The magnetoresistive element (hereinafter referred to as "rMR element") is made of Ni
-Fe, Ni-Co, etc. are used, and changes in the applied magnetic field can be detected by changes in the resistance of the thin film element. Therefore, if a permanent magnet or the like is used as a magnetic field generating means, it requires a light source such as an LED (light emitting diode), and is more durable than a photosensor, etc., which requires a consumable and continuous light source. You can get an excellent sensor.

The magnetic anisotropy of the MR element can be formed by the oblique incidence effect during film formation, the external magnetic field, the shape, and the like. Therefore, it is easy to create a configuration in which the flow of magnetic flux generated from the magnetization pattern recorded on the rotor, which is the object to be detected, is orthogonal to the magnetic anisotropy direction of the MR element. For example, since the rate of change in resistance of the MR element is at its maximum, the change in resistance at this time is converted into a signal and used for control of rotation speed, position detection, etc.

Conventionally, one method of using this is a capstan motor for a VTR (video tape recorder), in which a capstan motor is mounted on a substrate 1, facing a circumferentially magnetized rotor, as shown in the plan view of FIG. A magnetic sensor is provided in which MR elements 2 are arranged radially in the radial direction, and the MR elements 2 have a magnetic anisotropy direction 3 in a certain direction. Hey, 4 is an electrode.

This is an integral type magnetic sensor that detects uneven magnetization and deformation of the rotor with high precision by integrating the output of the MR element 2. A method was proposed to obtain an element with magnetic anisotropy in a certain direction by depositing the material while applying an external magnetic field.

(Problems to be Solved by the Invention) However, in the above conventional example, as shown in FIG. 4, the longitudinal direction of the MR element pattern and the magnetic anisotropy direction are different, so There is a problem that sufficient characteristics cannot be obtained.

Furthermore, Fig. 5 shows the R-H characteristics when the angle θ between the longitudinal direction of the MR element pattern and the magnetic anisotropy direction is varied between 0 and 90 degrees. As the temperature approaches , the rate of change in resistance decreases and bisteresis occurs, which cause sensor malfunctions and are problems that must be solved.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to obtain a surface-facing magnetic sensor that enables extremely high-precision position detection and control.

(Means for Solving the Problems) The present invention provides a surface-sealed magnetic sensor by forming the magnetic anisotropy of an MR element in a radial direction facing a circumferentially magnetized rotor. The aim is to improve the characteristics of

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on FIGS. 1 and 2.

In FIG. 1 showing a front view of a surface-facing magnetic sensor according to the present invention, 1 is a substrate, 2 is an MR element arranged radially on the surface of the substrate, and is made of Ni-Co.

It is obtained by forming an MRM film of Ni--Fe or the like using vacuum thin film formation technology, and then forming a zigzag pattern along concentric circles using photolithography etching technology. Reference numeral 13 denotes the magnetic anisotropy direction of the MR element 2, which is formed radially in the radial direction from the center of the concentric circles, and the method of forming it will be described below.

In FIG. 2, which shows the manufacturing process of the magnetic sensor according to the present invention in longitudinal cross-sectional views, when forming an MR film 12 on the substrate 1 shown in FIG. A magnetic field generation source 5 that generates a magnetic field radially in the radial direction is installed on the back side of the substrate 1. According to this method, radial magnetic anisotropy is formed in the radial direction without being affected by magnetic anisotropy formed by the incident effect or shape effect during film formation.

Next, a zigzag pattern of the MR element 2 is formed using the etching technique described above, as shown in FIG. 2C. (
(See also FIG. 1) Another example of the manufacturing method is shown in the process diagram of FIG. 3. This is because the throat <
After forming the MR film 12, as shown in FIG. 2(f), a magnetic field generation source 5 that generates a radial magnetic field is installed on the back side of the substrate 1 or on the front side of the MRIIIi 12, and heat treatment is performed in a vacuum. By performing this, radial magnetic anisotropy can be formed in the longitudinal direction of the MR film 12. Figure 5A (g) is a completed diagram of the magnetic sensor.

[Effects of the Invention] As explained above, the present invention provides a radially extending MR
Because the element pattern is formed and its magnetic anisotropy is applied in the radial direction, when used in a surface-facing magnetic sensor, it has significantly improved performance compared to conventional magnetic sensors, and can be used in extremely highly invasive positions. It has the effect of being able to be detected and controlled.

[Brief explanation of drawings]

FIG. 1 is a front view of a surface-facing magnetic sensor embodying the present invention, and FIG. 2 is a manufacturing process diagram also shown in longitudinal cross-sectional view, where (a) is a diagram of the substrate and (b) is a diagram of the manufacturing method. is a diagram during film formation, Figure <c> is a completed diagram after etching, Figure 3 is a process diagram of another example of the same manufacturing method, Figure (d) is a diagram of the substrate,
Figure 4(e) is a diagram after film formation is completed, Figure 4(f) is a diagram during heat treatment, Figure 4(g) is a completed diagram after etching treatment, and Figure 4 is a front view of a conventional magnetic sensor. FIG. 5 is a graph showing the relationship between the angle between the longitudinal direction of the MR element pattern and the anisotropy direction and the R-H characteristic. 2... Magnetoresistive element 5-----Radial magnetic field generation source

Claims (3)

[Claims] (1) A magnetic sensor in which a magnetoresistive element is disposed in a radial direction facing a circumferentially magnetized rotor,
A magnetic sensor, wherein the magnetoresistive element has magnetic anisotropy in the radial direction. (2) In a magnetic sensor in which magnetoresistive elements are arranged radially facing a circumferentially magnetized rotor,
A method for manufacturing a magnetic sensor, characterized in that when forming a magnetoresistive film, magnetic anisotropy is imparted in the radial direction using a magnetic field generation source that generates a radial magnetic field. (3) In a magnetic sensor in which magnetoresistive elements are arranged radially opposite a circumferentially magnetized rotor,
A method for manufacturing a magnetic sensor, characterized in that after forming a magnetoresistive film, magnetic anisotropy is imparted in the radial direction by heat treatment using a magnetic field generation source that generates a magnetic field in the radial direction.