Magnetic sensor

Abstract

The present invention provides a magnetic sensor comprising: a magnetoresistive sensor; the first magnetic flux collector is located on one side of the magnetic resistance sensor, and the first magnetic flux collector and the magnetic resistance sensor are spaced from each other; the second magnetic flux collector is located on the other side of the magnetic resistance sensor, and the second magnetic flux collector and the magnetic resistance sensor are spaced from each other; wherein the magnetoresistance sensor, the first magnetic flux collector and the second magnetic flux collector have the same multilayer film structure, and are prepared at the same time through the same technological process. Compared with the prior art, the invention has the advantages of low manufacturing cost, low hysteresis and high sensitivity.

Description

[Technical Field]

[0001] This invention relates to the field of magnetic sensor technology, and in particular to a magnetic sensor with low hysteresis and high sensitivity. [Background Technology]

[0002] Magnetoresistive sensors are widely used in consumer electronics, industrial, and automotive fields, such as electronic compasses, current sensors, angle sensors, speed sensors, and switch sensors. Traditionally, to improve the sensitivity of magnetoresistive sensors, a soft magnetic film is grown on top of the sensor after its initial fabrication and patterned into an anisotropic flux concentrator. The disadvantages are: firstly, it increases the complexity of the process and manufacturing costs; secondly, the anisotropic flux concentrator exhibits significant hysteresis after magnetic field interference, leading to a decrease in the accuracy of the magnetoresistive sensor.

[0003] Therefore, it is necessary to propose a new technical solution to address the above problems. [Summary of the Invention]

[0004] The purpose of this invention is to provide a magnetic sensor that is not only low in manufacturing cost, but also has low hysteresis and high sensitivity.

[0005] To achieve the objective of the invention, according to one aspect of the present invention, a magnetic sensor is provided, comprising: a magnetoresistive sensor; a first flux concentrator located on one side of the magnetoresistive sensor, wherein the first flux concentrator and the magnetoresistive sensor are spaced apart from each other; and a second flux concentrator located on the other side of the magnetoresistive sensor, wherein the second flux concentrator and the magnetoresistive sensor are spaced apart from each other; wherein the magnetoresistive sensor, the first flux concentrator, and the second flux concentrator have the same multilayer film structure and are fabricated simultaneously through the same process flow.

[0006] Furthermore, the multilayer film structure includes a ferromagnetic free layer; the ferromagnetic free layer of the magnetoresistive sensor, the ferromagnetic free layer of the first flux concentrator, and the ferromagnetic free layer of the second flux concentrator all have a vortex-like magnetization configuration.

[0007] Furthermore, the first flux concentrator, the magnetoresistive sensor, and the second flux concentrator are arranged sequentially along the x-axis; the x-axis is parallel to the surface of the multilayer film structure.

[0008] Furthermore, the first and second flux aggregators have the same shape and size; the first and second flux aggregators are symmetrical about the magnetoresistive sensor.

[0009] Furthermore, the multilayer film structure also includes a buffer layer, an antiferromagnetic layer, a ferromagnetic layer, a metal layer, a ferromagnetic reference layer, a barrier layer, and a capping layer, which are stacked sequentially from bottom to top.

[0010] Furthermore, the magnetization direction of the ferromagnetic reference layer is along the x-direction; the ferromagnetic layer forms an antiferromagnetic coupling with the ferromagnetic reference layer through the metal layer; the antiferromagnetic layer pins the magnetization direction of the ferromagnetic layer through an exchange biasing effect.

[0011] Furthermore, the magnetoresistive sensor has a cylindrical structure with a diameter of Ds; the first magnetic flux concentrator has a cylindrical structure with a diameter of Dc1; and the second magnetic flux concentrator has a cylindrical structure with a diameter of Dc2.

[0012] Furthermore, diameter Dc2 = diameter Dc1 >= diameter Ds.

[0013] Furthermore, the applied magnetic field Hx is less than the saturation magnetic field Hs of the ferromagnetic free layer of the first magnetic flux concentrator and the ferromagnetic free layer of the second magnetic flux concentrator, where Hs = (π*t*Ms) / (4*D), D is the diameter of the ferromagnetic free layer of the first magnetic flux concentrator and the ferromagnetic free layer of the second magnetic flux concentrator, and t is the thickness of the ferromagnetic free layer.

[0014] Furthermore, the diameter Dc1 of the first magnetic flux aggregator is between 0.2um and 20um; the diameter Dc2 of the second magnetic flux aggregator is between 0.2um and 20um; the diameter Ds of the magnetoresistive sensor is between 0.2um and 5um; and the thickness of the ferromagnetic free layer is between 10nm and 200nm.

[0015] Compared with existing technologies, the present invention not only has low manufacturing cost, but also low hysteresis and high sensitivity. [Attached Image Description]

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0017] Figure 1 This is a schematic diagram of the structure of a magnetic sensor in one embodiment of the present invention;

[0018] Figure 2 For example, in one embodiment of the present invention Figure 1The diagram shows the vortex magnetization configuration of the ferromagnetic free layer of the magnetoresistive sensor, the ferromagnetic free layer of the first flux concentrator, and the ferromagnetic free layer of the second flux concentrator under the magnetic field conditions of Hx = 0G, Hx = 50G, and Hx returning to 0G.

[0019] Figure 3 For example, in one embodiment of the present invention Figure 1 The magnetization curves of the ferromagnetic free layer of the magnetoresistive sensor, the ferromagnetic free layer of the first flux concentrator, and the ferromagnetic free layer of the second flux concentrator are shown.

Detailed Implementation Methods

[0020] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] The term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the invention. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that excludes other embodiments. Unless otherwise specified, the terms coupling, connection, linking, and interconnection used herein to indicate electrical connection mean direct or indirect connection. For example, A being connected to B includes both a direct electrical connection between A and B and a connection between A and B via electrical components or circuits.

[0022] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0023] Please refer to Figure 1 As shown, it is a schematic diagram of the structure of a magnetic sensor in one embodiment of the present invention.

[0024] Figure 1The magnetic sensor shown includes a magnetoresistive sensor 101, a first flux concentrator 102, and a second flux concentrator 103. The first flux concentrator 102 is located on one side (e.g., the left side) of the magnetoresistive sensor 101, and the first flux concentrator 102 and the magnetoresistive sensor 101 are spaced apart. The second flux concentrator 103 is located on the other side (e.g., the right side) of the magnetoresistive sensor 101, and the second flux concentrator 103 and the magnetoresistive sensor 101 are spaced apart. The magnetoresistive sensor 101, the first flux concentrator 102, and the second flux concentrator 103 have the same multilayer film structure (not identified) and are fabricated simultaneously using the same process.

[0025] For ease of description, Figure 1 The system defines a Cartesian coordinate system, in which the X-axis extends from left to right, the Z-axis extends from bottom to top, and the Y-axis extends away from the observer and into the page. The Z-axis, X-axis, and Y-axis satisfy the right-hand rule. The plane defined by the X-axis and Y-axis is parallel to the surface of the multilayer membrane structure (unlabeled).

[0026] The magnetoresistive sensor 101 is patterned as a circle with a diameter Ds that can be 0.2µm-5µm. From bottom to top, it includes: a buffer layer 101h, an antiferromagnetic layer 101g, a ferromagnetic layer 101f, a metal layer 101e, a ferromagnetic reference layer 101d, a barrier layer 101c, a ferromagnetic free layer 101b, and a capping layer 101a. The ferromagnetic free layer 101b has a vortex magnetization configuration. The magnetization direction of the ferromagnetic reference layer 101d is along the x-direction. The ferromagnetic layer 101f forms an antiferromagnetic coupling with the ferromagnetic reference layer 101d through the metal layer 101e. The antiferromagnetic layer 101g pins the magnetization direction of the ferromagnetic layer 101f through an exchange bias. The thickness t of the ferromagnetic free layer 101b can be 10nm-200nm. The first flux concentrator 102 is patterned as a circle with a diameter Dc that can be 0.2um-20um and Dc>=Ds. From bottom to top, it includes: a buffer layer 102h, an antiferromagnetic layer 102g, a ferromagnetic layer 102f, a metal layer 102e, a ferromagnetic reference layer 102d, a barrier layer 102c, a ferromagnetic free layer 102b, and a capping layer 102a. The ferromagnetic free layer 102b has a vortex magnetization configuration. The magnetization direction of the ferromagnetic reference layer 102d is along the x-direction. The ferromagnetic layer 102f forms an antiferromagnetic coupling with the ferromagnetic reference layer 102d through the metal layer 102e. The antiferromagnetic layer 102g pins the magnetization direction of the ferromagnetic layer 102f through an exchange bias. The thickness t of the ferromagnetic free layer 102b can be 10nm-200nm. The second flux concentrator 103 is patterned into a circle with a diameter Dc that can be 0.2µm-20µm and a diameter Dc>=Ds. From bottom to top, it includes: a buffer layer 103h, an antiferromagnetic layer 103g, a ferromagnetic layer 103f, a metal layer 103e, a ferromagnetic reference layer 103d, a barrier layer 103c, a ferromagnetic free layer 103b, and a capping layer 103a. The ferromagnetic free layer 103b has a vortex magnetization configuration. The magnetization direction of the ferromagnetic reference layer 103d is along the x-direction. The ferromagnetic layer 103f forms an antiferromagnetic coupling with the ferromagnetic reference layer 103d through the metal layer 103e. The antiferromagnetic layer 103g pins the magnetization direction of the ferromagnetic layer 103f through an exchange bias. The thickness t of the ferromagnetic free layer 103b can be 10nm-200nm. The ferromagnetic free layer 102b of the first flux concentrator 102 and the ferromagnetic free layer 103b of the second flux concentrator 103 amplify the applied magnetic field in the x-direction, thereby significantly improving the sensitivity of the magnetoresistive sensor 101.For example, the diameter Dc of the magnetoresistive sensor 101 is 0.5 μm, the diameter Ds of the first flux concentrator 102 and the second flux concentrator 103 is 2 μm, the center distance S1 between the magnetoresistive sensor 101 and the first flux concentrator 102 and the second flux concentrator 103 is 1.5 μm, the thickness t of the ferromagnetic free layer 101b of the magnetoresistive sensor 101, the ferromagnetic free layer 102b of the first flux concentrator 102 and the ferromagnetic free layer 103b of the second flux concentrator 103 is 50 nm, and the ferromagnetic free layer 102b of the first flux concentrator 102 and the ferromagnetic free layer 103b of the second flux concentrator 103 can amplify the external magnetic field by 1.9 times, thereby significantly improving the sensitivity of the magnetoresistive sensor 101.

[0027] In conclusion, Figure 1 The multilayer film structure (not labeled) in the magnetic sensor shown includes ferromagnetic free layers (101b, 102b, 103b). The ferromagnetic free layer 101b of the magnetoresistive sensor 101, the ferromagnetic free layer 102b of the first flux concentrator 102, and the ferromagnetic free layer 103b of the second flux concentrator 103 all have a vortex-like magnetization configuration.

[0028] exist Figure 1 In the embodiment shown, the first flux concentrator 102, the magnetoresistive sensor 101, and the second flux concentrator 103 are arranged sequentially along the x-axis, which is parallel to the surface of the multilayer film structure (not labeled).

[0029] exist Figure 1 In the embodiment shown, the first flux aggregator 102 and the second flux aggregator 103 have the same shape and size; the first flux aggregator 102 and the second flux aggregator 103 are symmetrical about the magnetoresistive sensor.

[0030] exist Figure 1In the specific embodiment shown, the multilayer film structure (not labeled) further includes buffer layers (101h, 102h, 103h), antiferromagnetic layers (101g, 102g, 103g), ferromagnetic layers (101f, 102f, 103f), metal layers (101e, 102e, 103e), ferromagnetic reference layers (101d, 102d, 103d), barrier layers (101c, 102c, 103c), and capping layers (101a, 102a, 103a). The buffer layers... The following layers are stacked sequentially from bottom to top: (101h, 102h, 103h), antiferromagnetic layer (101g, 102g, 103g), ferromagnetic layer (101f, 102f, 103f), metal layer (101e, 102e, 103e), ferromagnetic reference layer (101d, 102d, 103d), barrier layer (101c, 102c, 103c), ferromagnetic free layer (101b, 102b, 103b), and capping layer (101a, 102a, 103a).

[0031] exist Figure 1 In the specific embodiment shown, the magnetization direction of the ferromagnetic reference layers (101d, 102d, 103d) is along the x-direction; the ferromagnetic layers (101f, 102f, 103f) form antiferromagnetic coupling with the ferromagnetic reference layers (101d, 102d, 103d) through the metal layers (101e, 102e, 103e); the antiferromagnetic layers (101g, 102g, 103g) pin the magnetization direction of the ferromagnetic layers (101f, 102f, 103f) through the exchange biasing effect.

[0032] exist Figure 1 In the specific embodiment shown, the magnetoresistive sensor 101 has a cylindrical structure with a diameter of Ds; the first magnetic flux concentrator 102 has a cylindrical structure with a diameter of Dc1; and the second magnetic flux concentrator 103 has a cylindrical structure with a diameter of Dc2. Wherein, diameter Dc2 = diameter Dc1 >= Ds.

[0033] exist Figure 1 In the specific embodiment shown, the diameter Dc1 of the first magnetic flux concentrator 102 is between 0.2um and 20um; the diameter Dc2 of the second magnetic flux concentrator 103 is between 0.2um and 20um; the diameter Ds of the magnetoresistive sensor 101 is between 0.2um and 5um; and the thickness of the ferromagnetic free layers (101b, 102b, 103b) is between 10nm and 200nm.

[0034] Please refer to Figure 2 As shown, this is one embodiment of the present invention. Figure 1The diagram shows the vortex magnetization configuration of the ferromagnetic free layer of the magnetoresistive sensor, the ferromagnetic free layer of the first flux concentrator, and the ferromagnetic free layer of the second flux concentrator under the magnetic field conditions of Hx = 0G, Hx = 50G, and Hx returning to 0G.

[0035] In particular, 201a is a schematic diagram of the vortex-state magnetization configuration of the ferromagnetic free layer 101b of the magnetoresistive sensor 101, the ferromagnetic free layer 102b of the first magnetic flux concentrator 102, and the ferromagnetic free layer 103b of the second magnetic flux concentrator 103 under the condition of Hx=0G, with the central black dot representing the vortex-state core and the magnetization direction being the z-direction; 201b represents the ferromagnetic free layer 101b of the magnetoresistive sensor 101, the ferromagnetic free layer 102b of the first magnetic flux concentrator 102, and the ferromagnetic free layer 103b of the second magnetic flux concentrator 103. A schematic diagram of the vortex magnetization configuration of the ferromagnetic free layer 103b of the flux collector 103 under the condition of Hx = 50G, with the vortex core moving along the y direction; 201c is a schematic diagram of the vortex magnetization configuration of the ferromagnetic free layer 101b of the magnetoresistive sensor 101, the ferromagnetic free layer 102b of the first flux collector 102, and the ferromagnetic free layer 103b of the second flux collector 103 under the condition that Hx returns to 0G, with the vortex core moving back to the center along the -y direction and low hysteresis.

[0036] Please refer to Figure 3 As shown, this is one embodiment of the present invention. Figure 1 The magnetization curves of the ferromagnetic free layer of the magnetoresistive sensor, the ferromagnetic free layer of the first flux concentrator, and the ferromagnetic free layer of the second flux concentrator are shown.

[0037] As Hx increases from 0 to Hs, the ferromagnetic free layer maintains its vortex-like magnetization configuration. The normalized magnetization M / Ms gradually increases with increasing Hx, where Hs is the saturation magnetic field with a value of (π*t*Ms) / (4*D), where D is the diameter of the ferromagnetic free layer and t is the thickness of the ferromagnetic free layer. When Hx > Hs, the magnetization direction of the ferromagnetic free layer is parallel to Hx. As Hx decreases to the nucleation magnetic field Hn, the magnetization direction of the ferromagnetic free layer remains parallel to Hx. When Hx is less than Hn, the ferromagnetic free layer returns to the vortex state. Therefore, to maintain low hysteresis, the applied magnetic field Hx should be less than the saturation magnetic field Hs2 of the ferromagnetic free layer 102b of the first flux concentrator 102 and the ferromagnetic free layer 103b of the second flux concentrator 103.

[0038] In summary, the present invention provides a low-hysteresis, high-sensitivity magnetic sensor: Firstly, the magnetoresistive sensor 101, the first flux concentrator 102, and the second flux concentrator 103 have the same multilayer film structure and are fabricated simultaneously through the same process, resulting in low manufacturing cost; Secondly, the ferromagnetic free layer 101b of the magnetoresistive sensor 101, the ferromagnetic free layer 102b of the first flux concentrator 102, and the ferromagnetic free layer 103b of the second flux concentrator 103 have a vortex-like magnetization configuration, resulting in low hysteresis after magnetic field interference; Thirdly, the ferromagnetic free layer 102b of the first flux concentrator 102 and the ferromagnetic free layer 103b of the second flux concentrator 103 amplify the applied magnetic field, thereby significantly improving the sensitivity of the magnetoresistive sensor.

[0039] In this invention, terms such as “connection,” “linked,” “connected,” and “joined” that indicate electrical connection, unless otherwise specified, indicate direct or indirect electrical connection.

[0040] The above description is only a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. Any equivalent modifications or changes made by those skilled in the art based on the disclosure of the present invention should be included within the scope of protection set forth in the claims.

Claims

1. A magnetic sensor, characterized in that, It includes: magnetoresistive sensor; A first magnetic flux concentrator is located on one side of the magnetoresistive sensor, and the first magnetic flux concentrator and the magnetoresistive sensor are spaced apart from each other. A second flux concentrator is located on the other side of the magnetoresistive sensor, and the second flux concentrator and the magnetoresistive sensor are spaced apart from each other; The magnetoresistive sensor, the first flux concentrator, and the second flux concentrator have the same multilayer film structure and are fabricated simultaneously using the same process.

2. The magnetic sensor according to claim 1, characterized in that, The multilayer membrane structure includes a ferromagnetic free layer; The ferromagnetic free layer of the magnetoresistive sensor, the ferromagnetic free layer of the first flux concentrator, and the ferromagnetic free layer of the second flux concentrator all have a vortex-like magnetization configuration.

3. The magnetic sensor according to claim 2, characterized in that, The first magnetic flux concentrator, the magnetoresistive sensor, and the second magnetic flux concentrator are arranged sequentially along the x-axis; The x-axis is parallel to the surface of the multilayer film structure.

4. The magnetic sensor according to claim 3, characterized in that, The first and second flux concentrators have the same shape and size; The first and second flux concentrators are symmetrical about the magnetoresistive sensor.

5. The magnetic sensor according to claim 3, characterized in that, The multilayer film structure further includes a buffer layer, an antiferromagnetic layer, a ferromagnetic layer, a metal layer, a ferromagnetic reference layer, a barrier layer, and a capping layer. The buffer layer, antiferromagnetic layer, ferromagnetic layer, metal layer, ferromagnetic reference layer, barrier layer, ferromagnetic free layer and cover layer are stacked sequentially from bottom to top.

6. The magnetic sensor according to claim 5, characterized in that, The magnetization direction of the ferromagnetic reference layer is along the x-direction; The ferromagnetic layer forms an antiferromagnetic coupling with the ferromagnetic reference layer through the metal layer; The antiferromagnetic layer pins the magnetization direction of the ferromagnetic layer through an exchange bias.

7. The magnetic sensor according to any one of claims 2-6, characterized in that, The magnetoresistive sensor has a cylindrical structure with a diameter of Ds; The first flux concentrator is a cylindrical structure with a diameter of Dc1; The second flux concentrator is a cylindrical structure with a diameter of Dc2.

8. The magnetic sensor according to claim 7, characterized in that, Diameter Dc2 = Diameter Dc1 >= Diameter Ds.

9. The magnetic sensor according to claim 8, characterized in that, The applied magnetic field Hx is less than the saturation magnetic field Hs of the ferromagnetic free layer of the first magnetic flux concentrator and the ferromagnetic free layer of the second magnetic flux concentrator. Where Hs=(π*t*Ms) / (4*D), D is the diameter of the ferromagnetic free layer of the first flux concentrator and the ferromagnetic free layer of the second flux concentrator, and t is the thickness of the ferromagnetic free layer.

10. The magnetic sensor according to claim 7, characterized in that, The diameter Dc1 of the first flux concentrator is between 0.2µm and 20µm; The diameter Dc2 of the second flux concentrator is between 0.2µm and 20µm; The diameter Ds of the magnetoresistive sensor is between 0.2um and 5um; The thickness of the ferromagnetic free layer is between 10 nm and 200 nm.

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