Yamaha Corporation

Kokichi Aiso

Yukio Wakui

Hideki Sato

Susumu Yoshida

Toshiyuki Oohashi

A magnetic sensor for detecting magnetism in two-axial directions or three-axial directions is constituted of a substrate, a silicon oxide film that is formed on the substrate so as to form the planar surface and slopes, a plurality of magnetoresistive elements, each of which is formed by laminating a free layer, a conductive layer, and a pin layer on the substrate, a plurality of lead films that are formed to connect the magnetoresistive elements in series, a CVD oxide film for covering the magnetoresistive elements, and a non-magnetic film that is formed between the magnetoresistive elements and the CVD oxide film so as to cover the periphery of the free layer with respect to each magnetoresistive element. Thus, it is possible for the magnetic sensor to include the magnetoresistive elements having superior hysteresis characteristics.

Magnetic sensor and manufacturing method therefor

A magnetic sensor includes a plurality of giant magnetoresistive elements, each of which includes a free layer, a conductive layer, and a pin layer sequentially laminated on a substrate, wherein the pin layer formed by sequentially laminating a first magnetic layer, an Ru layer, a second magnetic layer, and an antiferromagnetic layer is subjected to magnetization heat treatment so as to fix the magnetization direction thereof. The first and second magnetic layers differ from each other in thickness and magnetic moment thereof, and the thickness of the Ru layer ranges from 4 &#x212b; to 10 &#x212b;. The magnetization heat treatment is performed so as to maintain an anti-parallel state between the first and second magnetic layers. In order to detect magnetic fields in three-axial directions, one giant magnetoresistive element is formed using a planar surface, and the other giant magnetoresistive elements are formed using respective slopes on the substrate.

A magnetic sensor comprises a substrate, magnetoresistive element of a spin-valve type, a bias magnetic layer (or a permanent magnet film), and a protective film, wherein the bias magnetic layer is connected with both ends of the magnetoresistive element and the upper surface thereof is entirely covered with the lower surface of the magnetoresistive element at both ends. Herein, distances between the side surfaces of the both ends of the magnetoresistive element and the side surfaces of the bias magnetic layer viewed from the protective film do not exceed 3 &#x3bc;m. In addition, a part of the bias magnetic layer can be covered with both ends of the magnetoresistive element, and an intermediate layer is arranged in relation to the magnetoresistive element, bias magnetic layer, and protective film so as to entirely cover the upper surface of the bias magnetic layer.

On a single chip are formed a plurality of magnetoresistance effect elements provided with pinned layers having fixed magnetization axes in the directions that cross each other. On a substrateare formed magnetic layers that will become two magnetic tunnel effect elementsas magnetoresistance effect elements. Magnetic-field-applying magnetic layers made of NiCo are formed to sandwich the magnetic layers in plan view. A magnetic field is applied to the magnetic-field-applying magnetic layers. The magnetic field is removed after the magnetic-field-applying magnetic layers are magnetized in the direction shown by arrow A. As a result of this, by the residual magnetization of the magnetic-field-applying magnetic layers, magnetic fields in the directions shown by arrows B are applied to the magnetic layers that will become magnetic tunnel effect elements, whereby the magnetization of the pinned layers of the magnetic layers that will become magnetic tunnel effect elementsis pinned in the directions shown by arrows B.

Magnetic sensor formed of magnetoresistance effect elements

A magnetic sensor comprises magnetoresistive elements and permanent magnet films, which are combined together to form GMR elements formed on a quartz substrate having a square shape, wherein the permanent magnet films are paired and connected to both ends of the magnetoresistive elements, so that an X-axis magnetic sensor and a Y-axis magnetic sensor are realized by adequately arranging the GMR elements relative to the four sides of the quartz substrate. Herein, the magnetization direction of the pinned layer of the magnetoresistive element forms a prescribed angle of 45&#xb0; relative to the longitudinal direction of the magnetoresistive element or relative to the magnetization direction of the permanent magnet film. Thus, it is possible to reliably suppress offset variations of bridge connections of the GMR elements even when an intense magnetic field is applied; and it is therefore possible to noticeably improve the resistant characteristics to an intense magnetic field.

Manufacturing method of a magnetic sensor

Magnetic sensor

A magnetic sensor includes eight SAF-type GMR elements. Four of the GMR elements detect a magnetic field in the direction of the X-axis and are bridge-connected to thereby constitute an X-axis magnetic sensor. The other four GMR elements detect a magnetic field in the direction of the Y-axis and are bridge-connected to thereby constitute a Y-axis magnetic sensor. The magnetization of a pinned layer of each of the GMR elements is pinned in a fixed direction by means of a magnetic field that a permanent bar magnet inserted into a square portion of a yoke of a magnet array generates in the vicinity of a rectangular portion of the yoke. A magnetic field generated in the vicinity of a certain rectangular portion of the yoke differs in direction by 90 degrees from a magnetic field generated in the vicinity of a rectangular portion adjacent to the former rectangular portion.

Method for manufacturing magnetic sensor, magnet array used in the method, and method for manufacturing the magnet array

On a single chip are formed a plurality of magnetoresistance effect elements provided with pinned layers having fixed magnetization axes in the directions that cross each other. On a substrateare formed magnetic layers that will become two magnetic tunnel effect elementsas magnetoresistance effect elements. Magnetic-field-applying magnetic layers made of NiCo are formed to sandwich the magnetic layers in plan view. A magnetic field is applied to the magnetic-field-applying magnetic layers. The magnetic field is removed after the magnetic-field-applying magnetic layers are magnetized in the direction shown by arrow A. As a result of this, by the residual magnetization of the magnetic-field-applying magnetic layers, magnetic fields in the directions shown by arrows B are applied to the magnetic layers that will become magnetic tunnel effect elementswhereby the magnetization of the pinned layers of the magnetic layers that will become magnetic tunnel effect elementsis pinned in the directions shown by arrows B.

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Hamamatsu, Japan

Kokichi Aiso