US-20260128202-A1 - METHOD FOR MANUFACTURING MAGNETIC LAMINATED BODY AND MAGNETIC SENSOR, AND APPARATUS FOR MANUFACTURING MAGNETIC LAMINATED BODY

US20260128202A1US 20260128202 A1US20260128202 A1US 20260128202A1US-20260128202-A1

Abstract

A laminated film comprising a ferromagnetic layer and an antiferromagnetic layer is formed in which the ferromagnetic layer and the antiferromagnetic layer are in contact with each other in a first direction. A magnetically pinned layer, which has a pinned magnetization direction with respect to an external magnetic field, is formed from the ferromagnetic layer by applying a magnetic field in the first direction to the laminated film. After stopping the application of the magnetic field, the magnetic laminated body is formed by heating the laminated film to a temperature equal to or higher than the blocking temperature of the antiferromagnetic layer.

Inventors

Hiroki Omura

Assignees

TDK CORPORATION

Dates

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

Claims (14)

1 . A method for manufacturing a magnetic laminated body comprising steps of: forming a laminated film comprising a ferromagnetic layer and an antiferromagnetic layer in which the ferromagnetic layer and the antiferromagnetic layer are in contact with each other in a first direction; forming, from the ferromagnetic layer, a magnetically pinned layer that has a pinned magnetization direction with respect to an external magnetic field by applying a magnetic field in the first direction to the laminated film; and after stopping application of the magnetic field, heating the laminated film to a temperature equal to or higher than a blocking temperature of the antiferromagnetic layer to form the magnetic laminated body.
2 . The method for manufacturing a magnetic laminated body according to claim 1 , wherein the laminated film is heated by a laser beam.
3 . The method for manufacturing a magnetic laminated body according to claim 1 , wherein, after stopping application of the magnetic field, the laminated film is transferred for heating of the laminated film.
4 . The method for manufacturing a magnetic laminated body according to claim 1 , wherein the laminated film comprises a magnetically free layer whose magnetization direction changes with respect to an external magnetic field, and a nonmagnetic layer, and the ferromagnetic layer, the antiferromagnetic layer, the magnetically free layer, and the nonmagnetic layer are arranged in the order of the magnetically free layer, the nonmagnetic layer, the ferromagnetic layer, and the antiferromagnetic layer in the first direction.
5 . The method for manufacturing a magnetic laminated body according to claim 1 , wherein the laminated film comprises a magnetically free layer whose magnetization direction changes with respect to an external magnetic field, a nonmagnetic layer, an intermediate ferromagnetic layer, and an intermediate layer that is formed from a nonmagnetic metal, and the ferromagnetic layer, the antiferromagnetic layer, the magnetically free layer, the nonmagnetic layer, the intermediate ferromagnetic layer, and the intermediate layer are arranged in the order of the magnetically free layer, the nonmagnetic layer, the intermediate ferromagnetic layer, the intermediate layer, the ferromagnetic layer, and the antiferromagnetic layer in the first direction.
6 . The method for manufacturing a magnetic laminated body according to claim 5 , wherein, when magnetic moment of the intermediate ferromagnetic layer is M 1 and magnetic moment of the ferromagnetic layer is M 2 , |M 2 −M 1 |/M 1 is between 3% and 20%.
7 . The method for manufacturing a magnetic laminated body according to claim 5 , wherein magnitudes of perpendicular magnetic anisotropy of the intermediate ferromagnetic layer and the ferromagnetic layer are different from each other.
8 . The method for manufacturing a magnetic laminated body according to claim 5 , wherein the magnetization direction of the magnetically free layer has a vortex shape in a plane perpendicular to the first direction in a state in which the external magnetic field is not applied.
9 . The method for manufacturing a magnetic laminated body according to claim 5 , wherein the nonmagnetic layer comprises an insulating layer.
10 . A method for manufacturing a magnetic sensor comprising steps of: arranging a ferromagnetic layer, a magnetically free layer whose magnetization direction changes with respect to an external magnetic field, a nonmagnetic layer, and an antiferromagnetic layer in the order of the magnetically free layer, the nonmagnetic layer, the ferromagnetic layer, and the antiferromagnetic layer in a first direction; forming a group of a first element unit and a second element unit in which said first element unit and said second element unit are connected in series, wherein each of said first and second element units comprises laminated film in which said ferromagnetic layer and said antiferromagnetic layer are in contact with each other, and in which one end of the group is connected to a power supply and other end is grounded; providing an output section between the first element unit and the second element unit; forming, from the ferromagnetic layer of the first element unit, a magnetically pinned layer, which has a pinned magnetization direction with respect to an external magnetic field, by applying a first magnetic field in the first direction to the first element unit; after stopping application of the first magnetic field, heating the first element unit to a temperature equal to or higher than a blocking temperature of the antiferromagnetic layer of the first element unit; forming, from the ferromagnetic layer of the second element unit, a magnetically pinned layer, which has a pinned magnetization direction with respect to an external magnetic field, by applying a second magnetic field including a component in a direction opposite to the first direction to the second element unit; and after stopping application of the second magnetic field, heating the second element unit to a temperature equal to or higher than a blocking temperature of the antiferromagnetic layer of the second element unit.
11 . A method for manufacturing a magnetic sensor comprising steps of: arranging a ferromagnetic layer, a magnetically free layer whose magnetization direction changes with respect to an external magnetic field, a nonmagnetic layer, and an antiferromagnetic layer in the order of the magnetically free layer, the nonmagnetic layer, the ferromagnetic layer, and the antiferromagnetic layer in a first direction; forming a first group of a first element unit and a second element unit in which said first element unit and said second element unit are connected in series, and forming a second group of a third element unit and a fourth element unit in which said third element unit and said fourth element unit are connected in series, wherein each of the first to fourth element units comprises laminated film in which the ferromagnetic layer and the antiferromagnetic layer are in contact with each other and one end of each of the first and second groups is connected to a power supply and the other ends are grounded, and wherein the first element unit and the fourth element unit are arranged on the power-supply side, and the second element unit and the third element unit are arranged on the ground side; providing a differentiator for determining a difference between an output that is between the first element unit and the second element unit and an output that is between the third element unit and the fourth element unit; forming, from the ferromagnetic layers of the first and third element units, magnetically pinned layers, each of which having a pinned magnetization direction with respect to an external magnetic field, by applying a first magnetic field in the first direction to the first and third element units; after stopping application of the first magnetic field, heating the first and third element units to a temperature equal to or higher than blocking temperatures of the antiferromagnetic layers of the first and third element units; forming, from the ferromagnetic layers of the second and fourth element units, magnetically pinned layers, each of which having a pinned magnetization direction with respect to an external magnetic field, by applying a second magnetic field including a component in a direction opposite to the first direction to the second and fourth element units; and after stopping application of the second magnetic field, heating the second and fourth element units to a temperature equal to or higher than blocking temperatures of the antiferromagnetic layers of the second and fourth element units.
12 . The method for manufacturing a magnetic sensor according to claim 10 , wherein the second magnetic field is in a direction opposite to the first direction.
13 . An apparatus for manufacturing a magnetic laminated body comprising: a magnetic field application device that applies a magnetic field in a first direction to a laminated film of a wafer that comprises the laminated film, in which a ferromagnetic layer and an antiferromagnetic layer are in contact with each other in the first direction, to form a magnetically pinned layer from the ferromagnetic layer, wherein a magnetization direction of the magnetically pinned layer is pinned with respect to an external magnetic field; a heating device that heats the laminated film to a temperature equal to or higher than a blocking temperature of the antiferromagnetic layer; and a transfer device that transfers the wafer between the magnetic field application device and the heating device.
14 . The apparatus for manufacturing a magnetic laminated body according to claim 13 , wherein the heating device comprises a laser beam irradiation device for heating the laminated film with a laser beam.

Description

FIELD This application claims the benefit of Japanese Priority Patent Application No. 2024-192567 filed on Nov. 1, 2024, the entire contents of which are incorporated herein by reference. The present disclosure relates to a method for manufacturing a magnetic laminated body, a magnetic sensor, and an apparatus for manufacturing a magnetic laminated body. BACKGROUND JP2018-6598A describes a magnetic sensor comprising a magnetically free layer whose magnetization direction changes with respect to an external magnetic field, a magnetically pinned layer whose magnetization direction is pinned with respect to the external magnetic field, and a nonmagnetic layer located between the magnetically free layer and the magnetically pinned layer. The magnetization direction of the magnetically pinned layer reverses when subjected to a strong magnetic field, and the magnetization direction may remain pinned in the reversed direction. To avoid this, a technique is known of providing an antiferromagnetic layer to strongly pin the magnetization direction of the magnetically pinned layer by exchange coupling between the antiferromagnetic layer and the magnetically pinned layer, as described in JP2015-207625A. SUMMARY An object of the present disclosure is to provide a method for manufacturing a magnetic laminated body that allows simplification of a device for magnetizing a magnetically pinned layer and for heating an antiferromagnetic layer. The method for manufacturing a magnetic laminated body of the present disclosure comprises the following steps: forming a laminated film comprising a ferromagnetic layer and an antiferromagnetic layer, wherein the ferromagnetic layer and the antiferromagnetic layer are in contact with each other in a first direction; applying a magnetic field in the first direction to the laminated film to form, from the ferromagnetic layer, a magnetically pinned layer whose magnetization direction is pinned with respect to an external magnetic field; and, after stopping the application of the magnetic field, heating the laminated film to a temperature equal to or higher than the blocking temperature of the antiferromagnetic layer. 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. FIGS. 2A and 2B are schematic drawings showing a method of magnetizing a magnetically pinned layer and a method for heating a laminated film of the magnetic sensor shown in FIGS. 1A and 1B. FIG. 3 is a schematic drawing of a device for applying a magnetic field to and heating the magnetic sensor shown in FIGS. 1A and 1B. FIGS. 4A and 4B are schematic drawings of a magnetic sensor according to a second example embodiment. FIG. 5 is a drawing of a structure of a laminated film in the second example embodiment. FIG. 6 is a schematic drawing of a magnetic sensor according to a third example embodiment. FIGS. 7A-7D are schematic drawings showing a method of magnetizing a magnetically pinned layer and a method for heating a laminated film of the magnetic sensor shown in FIG. 6. FIG. 8 is a schematic drawing of a magnetic sensor according to a fourth example embodiment. FIGS. 9A-9D are schematic drawings showing a method of magnetizing a magnetically pinned layer and a method for heating a laminated film of the magnetic sensor shown in FIG. 8. FIGS. 10A and 10B are diagrams showing measurement results of magnetization curves in the examples and comparative examples. 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. A magnetically pinned layer of a magnetic sensor must be magnetized, and, for the