Magnetoresistive sensor and manufacturing method thereof

Patent metadata

Field	Value
Publication number	US-12256644-B2
Application number	US-202217580645-A
Country	US
Kind code	B2
Filing date	Jan 21, 2022
Priority date	Dec 7, 2021
Publication date	Mar 18, 2025
Grant date	Mar 18, 2025

Abstract

A magnetoresistive sensor and a manufacturing method thereof are provided. The method includes: forming an initial reference layer in an annular shape, wherein the initial reference layer includes an anti-ferromagnetic layer and a ferromagnetic layer; performing a heat treatment on the initial reference layer, wherein the ferromagnetic layer is magnetized to have a magnetization direction oriented along a vortex path during a heating step of the heat treatment, and an exchange bias oriented along the vortex path is induced at an interface of the anti-ferromagnetic layer and the ferromagnetic layer during a cooling step of the heat treatment; patterning the initial reference layer to form separated reference layers, wherein the reference layers are respectively formed in a annular sector shape, and the reference layers are arranged along the vortex path; forming spacer layers and free layers to form magnetoresistive devices; routing the magnetoresistive devices to form the magnetoresistive sensor.

First claim

What is claimed is:

1. A manufacturing method of a magnetoresistive sensor, comprising:
forming an initial reference layer in an annular shape, wherein the initial reference layer includes an antiferromagnetic layer with only a single side in contact with a ferromagnetic layer;
subjecting the initial reference layer to a heat treatment, wherein the ferromagnetic layer is magnetized and has a magnetization direction oriented along a vortex path during a heating step of the heat treatment, and an exchange bias oriented along the vortex path is generated at an interface between the antiferromagnetic layer and the ferromagnetic layer during a cooling step of the heat treatment;
patterning the initial reference layer to form separate reference layers, wherein the reference layers are respectively in an annular sector shape, and the reference layers are arranged along the vortex path;
forming spacer layers and free layers, to form magnetoresistive devices, wherein the magnetoresistive devices respectively comprise one of the reference layers and one of the free layers separated from each other by one of the spacer layers; and
routing the magnetoresistive device to form the magnetoresistive sensor,
wherein the initial reference layer is not applied with an external magnetic field in the cooling step during the heat treatment,
wherein the spacer layers and the free layers are formed after formation of the reference layers.

2. The manufacturing method of the magnetoresistive sensor according to claim 1 , wherein the initial reference layer is formed as a closed annulus pattern.

3. The manufacturing method of the magnetoresistive sensor according to claim 1 , wherein the initial reference layer is formed as an open annulus pattern.

4. The manufacturing method of the magnetoresistive sensor according to claim 1 , wherein the initial reference layer is formed as a circular annulus pattern or a polygonal annulus pattern.

5. The manufacturing method of the magnetoresistive sensor according to claim 1 , wherein different exchange biases of the reference layers follow the vortex path.

Assignees

• Univ Nat Tsing Hua

Inventors

• Lai Chih-Huang
• Lee Chia-Chang
• Yen Yu-Shen

Classifications

• H10N50/10

  Magnetoresistive devices · CPC title

• H01F10/3272

  by use of anti-parallel coupled [APC] ferromagnetic layers, e.g. artificial ferrimagnets [AFI], artificial [AAF] or synthetic [SAF] anti-ferromagnets · CPC title

• G01R33/093

  using multilayer structures, e.g. giant magnetoresistance sensors (thin magnetic films H01F10/00) · CPC title

• H01F41/303

  with exchange coupling adjustment of magnetic film pairs, e.g. interface modifications by reduction, oxidation · CPC title

• G01R33/0005

  Geometrical arrangement of magnetic sensor elements; Apparatus combining different magnetic sensor types (G01R33/0206 takes precedence) · CPC title