US-20260126502-A1 - MAGNETIC SENSOR AND METHOD FOR MANUFACTURING SAME

US20260126502A1US 20260126502 A1US20260126502 A1US 20260126502A1US-20260126502-A1

Abstract

A magnetic sensor comprising at least one magnetic field sensing element and at least one first soft magnetic layer. At least one magnetic field sensing element comprises a first magnetically pinned layer, a magnetically free layer whose magnetization direction changes with respect to an external magnetic field, and a first nonmagnetic layer. The first magnetically pinned layer, the magnetically free layer, and the first nonmagnetic layer are arranged in the order of the magnetically free layer, the first nonmagnetic layer, and the first magnetically pinned layer in a first direction. At least one first soft magnetic layer confronts the at least one magnetic field sensing element in the first direction.

Inventors

Hiroki Omura
Takafumi Kobayashi

Assignees

TDK CORPORATION

Dates

Publication Date: 20260507
Application Date: 20251023
Priority Date: 20241101

Claims (18)

1 . A magnetic sensor comprising at least one magnetic field sensing element and at least one first soft magnetic layer, wherein the at least one magnetic field sensing element comprises a first magnetically pinned layer, a magnetically free layer whose magnetization direction changes with respect to an external magnetic field, and a first nonmagnetic layer, the first magnetically pinned layer, the magnetically free layer, and the first nonmagnetic layer are arranged in the order of the magnetically free layer, the first nonmagnetic layer, and the first magnetically pinned layer in a first direction, a magnetization direction of the first magnetically pinned layer is pinned in the first direction, and the at least one first soft magnetic layer confronts the at least one magnetic field sensing element in the first direction.
2 . The magnetic sensor according to claim 1 comprising at least one second soft magnetic layer that confronts the at least one magnetic field sensing element in the first direction, wherein the at least one magnetic field sensing element is between the at least one first soft magnetic layer and the at least one second soft magnetic layer.
3 . The magnetic sensor according to claim 2 wherein the magnetically free layer has a long axis, at least one of the first soft magnetic layer and the second soft magnetic layer has a long axis, and the long axis of the magnetically free layer is parallel to the long axis of at least one of the first soft magnetic layer and the second soft magnetic layer.
4 . The magnetic sensor according to claim 1 , wherein the first nonmagnetic layer comprises an insulating layer.
5 . The magnetic sensor according to claim 1 , wherein the at least one magnetic field sensing element comprises a second magnetically pinned layer and an intermediate layer made of a nonmagnetic metal, the first magnetically pinned layer, the magnetically free layer, the first nonmagnetic layer, the second magnetically pinned layer and the intermediate layer are arranged in the order of the magnetically free layer, the first nonmagnetic layer, the first magnetically pinned layer, the intermediate layer, and the second magnetically pinned layer in the first direction, and a magnetization direction of the second magnetically pinned layer is pinned in the direction opposite to the magnetization direction of the first magnetically pinned layer.
6 . The magnetic sensor according to claim 1 , wherein the at least one magnetic field sensing element comprises a second magnetically pinned layer and a second nonmagnetic layer, the first magnetically pinned layer, the magnetically free layer, the first nonmagnetic layer, the second magnetically pinned layer, and the second nonmagnetic layer are arranged in the order of the second magnetically pinned layer, the second nonmagnetic layer, the magnetically free layer, the first nonmagnetic layer, and the first magnetically pinned layer in the first direction, and a magnetization direction of the second magnetically pinned layer is pinned in the direction opposite to the magnetization direction of the first magnetically pinned layer.
7 . The magnetic sensor according to claim 1 , wherein the at least one magnetic field sensing element comprises an antiferromagnetic layer, the first magnetically pinned layer, the magnetically free layer, the first nonmagnetic layer, and the antiferromagnetic layer are arranged in the order of the magnetically free layer, the first nonmagnetic layer, the first magnetically pinned layer, and the antiferromagnetic layer in the first direction, and the magnetization direction of the first magnetically pinned layer is pinned by exchange coupling with the antiferromagnetic layer.
8 . The magnetic sensor according to claim 1 , wherein the at least one magnetic field sensing element comprises an intermediate layer made of a nonmagnetic metal, a second magnetically pinned layer, and an antiferromagnetic layer, the first magnetically pinned layer, the magnetically free layer, the first nonmagnetic layer, the intermediate layer, the second magnetically pinned layer, and the antiferromagnetic layer are arranged in the order of the magnetically free layer, the first nonmagnetic layer, the first magnetically pinned layer, the intermediate layer, the second magnetically pinned layer, and the antiferromagnetic layer in the first direction, and a magnetization direction of the second magnetically pinned layer is pinned in a direction opposite to the magnetization direction of the first magnetically pinned layer by exchange coupling with the antiferromagnetic layer.
9 . The magnetic sensor according to claim 1 , wherein a magnetization direction of the magnetically free layer is oriented orthogonally to the first direction in the absence of an external magnetic field.
10 . The magnetic sensor according to claim 1 , wherein a magnetization direction of the magnetically free layer has a vortex shape in a plane perpendicular to the first direction in the absence of an external magnetic field.
11 . The magnetic sensor according to claim 10 , wherein the at least one magnetic field sensing element is a plurality of magnetic field sensing elements, a magnetization direction of the magnetically free layer of each magnetic field sensing element has a vortex shape in a plane perpendicular to the first direction in the absence of an external magnetic field, the plurality of magnetic field sensing elements is connected in series and confronts one the first soft magnetic layer in the first direction, and a portion of the plurality of magnetic field sensing elements and the remaining portion of the plurality of magnetic field sensing elements are on both sides of a plane containing a centerline of the first soft magnetic layer that is parallel to the first direction, and magnetization directions at the centers of the vortex shapes are opposite to each other.
12 . The magnetic sensor according to claim 1 , wherein said at least one magnetic field sensing element is a plurality of magnetic field sensing elements, the magnetic sensor comprises first and second element units each having a portion of the plurality of magnetic field sensing elements, the first and second element units are connected in series to form a group, one end of the group is connected to a power supply and the other end is grounded, an output section is located between the first element unit and the second element unit, and magnetization directions of the first magnetically pinned layers of the first element unit and magnetization directions of the first magnetically pinned layers of the second element unit are opposite to each other.
13 . The magnetic sensor according to claim 1 , wherein the at least one magnetic field sensing element is a plurality of magnetic field sensing elements, the magnetic sensor has first to fourth element units each having a portion of the plurality of magnetic field sensing elements, the first and second element units are connected in series to form a first group, the third and fourth element units are connected in series to form a second group, one end of the first group and the second group is connected to a power supply, and the other ends are grounded, the first element unit and the fourth element unit are located on the power-supply side, the second element unit and the third element unit are located on the ground side, the magnetic sensor includes a differentiator for determining a difference between output between the first element unit and the second element unit and output between the third element unit and the fourth element unit, magnetization directions of the first magnetically pinned layers of the first element unit and the first magnetically pinned layers of the third element unit are the same direction, and magnetization directions of the first magnetically pinned layers of the second and fourth element units are opposite to magnetization directions of the first magnetically pinned layers of the first and third element units.
14 . The magnetic sensor according to claim 13 , wherein the at least one first soft magnetic layer is a single first soft magnetic layer, and the single first soft magnetic layer confronts the first to fourth element units.
15 . A method of manufacturing a magnetic sensor comprising steps of: forming a group of a first element unit and a second element unit in which the first element unit and the second element unit are connected in series; and forming at least one magnetic field sensing element in each of the first and second element units by connecting one end of the group to a power supply, grounding the other end, and providing an output section between the first and second element units, wherein: the step of making at least one magnetic field sensing element in each of the first and second element units comprises: arranging a first magnetically pinned layer, a magnetically free layer whose magnetization direction changes with respect to an external magnetic field, a first nonmagnetic layer, and an antiferromagnetic layer in the order of the magnetically free layer, the first nonmagnetic layer, the first magnetically pinned layer, and the antiferromagnetic layer in a first direction; applying a magnetic field in the first direction to the first element unit while locally heating the first element unit to magnetize the first magnetically pinned layers of the first element unit; and applying a magnetic field in a second direction opposite to the first direction to the second element unit while locally heating the second element unit to magnetize the first magnetically pinned layers of the second element unit.
16 . The method of manufacturing a magnetic sensor according to claim 15 , wherein the first element unit and the second element unit are locally heated by irradiating a laser beam.
17 . A method of manufacturing a magnetic sensor comprising steps of: forming first to fourth element units such that a first group is provided in which a first element unit and a second element unit are connected in series, a second group is provided in which a third element unit and a fourth element unit are connected in series, one end of the first group and one end of the second group are connected to a power supply, the other ends are grounded, the first element unit and the fourth element unit are on the power-supply side, the second element unit and the third element unit are on the grounded side, and at least one magnetic field detecting element is provided in each of the first to fourth element units; and providing a differentiator for determining a difference between output between the first element unit and the second element unit and output between the third element unit and the fourth element unit, wherein: the step of providing at least one magnetic field detecting element of the first to fourth element units comprises: arranging a first magnetically pinned layer, a magnetically free layer whose magnetization direction changes with respect to an external magnetic field, a first nonmagnetic layer, and an antiferromagnetic layer in the order of the magnetically free layer, the first nonmagnetic layer, the first magnetically pinned layer, and the antiferromagnetic layer in a first direction; applying a magnetic field to the first and third element units in the first direction while locally heating the first and third element units to magnetize the first magnetically pinned layers of the first and third element units; and applying a magnetic field to the second and fourth element units in a second direction opposite to the first direction while locally heating the second and fourth element units to magnetize the first magnetically pinned layers of the second and fourth element units.
18 . The method of manufacturing a magnetic sensor according to claim 17 , wherein the first to fourth element units are locally heated by irradiating a laser beam.

Description

FIELD This application claims the benefit of Japanese Priority Patent Application No. 2024-192566 filed on November 1, 2024, the entire contents of which are incorporated herein by reference. The present disclosure relates to a magnetic sensor and a method for manufacturing same. BACKGROUND A magnetic sensor using a magnetoresistive effect generally comprises a magnetically free layer whose magnetization direction changes with respect to an external magnetic field, a magnetically pinned layer whose magnetization direction is pinned, and a nonmagnetic layer located between the magnetically free layer and the magnetically pinned layer. JP2018-6598A describes a magnetic sensor in which the magnetization direction of the magnetically pinned layer is pinned in the stacking direction of the magnetically free layer, the nonmagnetic layer, and the magnetically pinned layer. SUMMARY An object of the present disclosure is to provide a magnetic sensor in which the magnetization direction of a magnetically pinned layer is pinned in the stacking direction of a magnetically free layer, a nonmagnetic layer, and the magnetically pinned layer, and in which the magnetization direction of the magnetically pinned layer tends not to incline from the stacking direction. The magnetic sensor of the present disclosure comprises at least one magnetic field sensing element and at least one first soft magnetic layer. The at least one magnetic field sensing element comprises a first magnetically pinned layer, a magnetically free layer whose magnetization direction changes with respect to an external magnetic field, and a first nonmagnetic layer. The first magnetically pinned layer, the magnetically free layer, and the first nonmagnetic layer are arranged in the order of the magnetically free layer, the first nonmagnetic layer, and the first magnetically pinned layer in a first direction, and the magnetization direction of the first magnetically pinned layer is pinned in the first direction. The at least one first soft magnetic layer confronts the at least one magnetic field sensing element in the first direction. The above and other objects, features, and advantages of the present application will become apparent from the following detailed description with reference to the accompanying drawings which illustrate the present application. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification. The drawings illustrate example embodiments and, together with the specification, serve to explain the principles of the technology. FIGS. 1A and 1B are schematic drawings of a magnetic sensor according to a first example embodiment. FIG. 2 is a schematic drawing of a magnetic sensor according to a second example embodiment. FIG. 3 is a schematic drawing of a magnetic sensor according to a third example embodiment. FIG. 4 is a schematic drawing of a magnetic sensor according to a fourth example embodiment. FIG. 5 is a schematic drawing of a magnetic sensor according to a fifth example embodiment. FIGS. 6A-6C are schematic drawings of magnetic sensors according to a sixth example embodiment and comparative examples. FIG. 7 is a schematic drawing of a magnetic sensor according to a seventh example embodiment. FIG. 8 is a schematic drawing of a magnetic sensor according to an eighth example embodiment. FIG. 9 is a schematic drawing of a magnetic sensor according to a ninth example embodiment. DETAILED DESCRIPTION In the following, some example embodiments and modification examples of the technology are described in detail with reference to the accompanying drawings. Note that the following description is directed to illustrative examples of the disclosure and not to be construed as limiting the technology. Factors including, without limitation, numerical values, shapes, materials, components, positions of the components, and how the components are coupled to each other are illustrative only and not to be construed as limiting the technology. Further, elements in the following example embodiments which are not recited in a most-generic independent claim of the disclosure are optional and may be provided on an as-needed basis. The drawings are schematic and are not intended to be drawn to scale. Like elements are denoted with the same reference numerals to avoid redundant descriptions. In the magnetic sensor described in JP2018-6598A, the magnetization direction of a magnetically pinned layer is pinned in the stacking direction, but the magnetization direction of the magnetically pinned layer may incline from the stacking direction due to an external magnetic field orthogonal to the stacking direction. The inclination of the magnetization direction of the magnetically pinned layer may cause a decrease in the output of the magnetic sensor. Some example embodiments of the present disclosure are described below with ref