Magnetic angle sensor and method for producing a magnetic angle sensor

Abstract

A magnetic angle sensor and a preparation method thereof, the magnetic angle sensor comprising: a substrate; a buffer layer on the substrate; four tunneling magnetoresistance sensor elements on a surface of the buffer layer, the magnetic moments of the pinning layers of the four tunneling magnetoresistance sensor elements being in the same direction; and a planar Hall sensor element on a surface of the buffer layer in a central region of the substrate, the four tunneling magnetoresistance sensor elements being uniformly arranged around the planar Hall sensor element. The present application improves the sensitivity and stability of the magnetic angle sensor by integrating the tunneling magnetoresistance sensor and the planar Hall sensor on the same substrate.

Description

Technical Field

[0001] This invention relates to the field of magnetic sensors, and more specifically to a magnetic angle sensor and its fabrication method. Background Technology

[0002] The core principle of a magnetic angle sensor is to detect changes in the direction of the magnetic field generated by a rotating magnet using a fixed-position magnetic-sensitive chip, and then calculate the precise angle using mathematical algorithms. This non-contact working mechanism gives it significant advantages such as high precision, long lifespan (no physical wear), strong environmental adaptability (dustproof, waterproof, and vibration-resistant), and ease of integration. Therefore, it is widely used in many critical fields requiring reliable angle measurement, such as automotive steering wheels and accelerator pedals, industrial robot joints, servo motors, and laptop hinges, becoming an important component for achieving precise motion control and intelligent interaction. Currently, sensors capable of 360-degree omnidirectional detection include Hall effect sensors, giant magnetoresistance (GMR) sensors, and tunnel magnetoresistance (TMR) sensors, but they all suffer from limited sensitivity and insufficient stability.

[0003] Please refer to Figure 1 Patent CN112097800B proposes a technical solution that combines anisotropic magnetoresistance (AMR) sensors with Hall sensors. However, on the one hand, the magnetic field generated by the Hall current will interfere with the measurement of magnetoresistance of the AMR sensor, requiring the two sensors to be set up vertically and separated by an isolation layer, which makes it impossible to achieve chip flattening. On the other hand, to use the Hall sensor to detect the in-plane magnetic field, it needs to be fabricated as a vertical Hall sensor, which is complex in terms of process. Summary of the Invention

[0004] The technical problem solved by this invention is to provide a magnetic angle sensor and its fabrication method, which improves the sensitivity and stability of the magnetic angle sensor by integrating a tunnel magnetoresistive sensor and a planar Hall sensor on the same substrate.

[0005] To solve the above-mentioned technical problems, the present invention provides a magnetic angle sensor, comprising: a substrate; a buffer layer located on the substrate; four tunnel magnetoresistive sensor elements, all located on the surface of the buffer layer, wherein the magnetic moment directions of the pinned layers of the four tunnel magnetoresistive sensor elements are consistent; and a planar Hall sensor element located on the surface of the buffer layer in the central region of the substrate, wherein the four tunnel magnetoresistive sensor elements are uniformly surrounding the planar Hall sensor element.

[0006] Optionally, the magnetic moment direction of the pinning layer is parallel to the surface of the substrate.

[0007] Optionally, the planar Hall sensor element includes a PHE membrane stack, first electrodes located on opposite sides of the PHE membrane stack, and second electrodes located on the other opposite sides of the PHE membrane stack, wherein the extending directions of the first electrodes and the extending directions of the second electrodes are perpendicular to each other.

[0008] Optionally, the PHE membrane stack includes a PHE buffer layer, a magnetically sensitive layer, and a PHE protective layer stacked sequentially from bottom to top.

[0009] Optionally, the tunnel magnetoresistive sensor element includes a bottom electrode, a TMR film stack, and a top electrode stacked from bottom to top.

[0010] Optionally, the TMR membrane stack includes, from bottom to top, a first TMR buffer layer, an antiferromagnetic layer, the pinning layer, a barrier layer, a free layer, and a second TMR buffer layer.

[0011] Accordingly, the present invention also provides a method for fabricating a magnetic angle sensor, comprising: providing a substrate; forming a buffer layer on the substrate; forming four tunnel magnetoresistive sensor elements on the surface of the buffer layer, wherein the magnetic moment directions of the pinned layers of the four tunnel magnetoresistive sensor elements are consistent; and after forming the tunnel magnetoresistive sensor elements, forming a planar Hall sensor element on the surface of the buffer layer in the central region of the substrate, wherein the four tunnel magnetoresistive sensor elements are uniformly surrounding the planar Hall sensor element.

[0012] Optionally, the method of forming the planar Hall sensor element includes: forming a PHE film stack on the surface of the buffer layer; forming a first electrode on each of the opposite sides of the PHE film stack; and forming a second electrode on the other opposite sides of the PHE film stack, wherein the extending directions of the first electrode and the extending directions of the second electrode are perpendicular to each other.

[0013] Optionally, the method of forming the tunnel magnetoresistive sensor element includes: forming a bottom electrode on the surface of the buffer layer; forming a TMR film stack on the surface of the bottom electrode; and forming a top electrode on the surface of the TMR film stack.

[0014] Optionally, before forming the buffer layer, an insulating layer is further formed on the surface of the substrate.

[0015] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: The magnetic angle sensor provided by this invention utilizes a four-tunnel magnetoresistive sensor element located on the surface of a buffer layer. Since the output signal of the tunnel magnetoresistive sensor element changes with the magnetic field direction angle over a period of 2π, it can detect in-plane angle changes from -180 degrees to 180 degrees. Similarly, the planar Hall sensor element, located on the surface of the buffer layer in the central region of the substrate, also has an output signal with a period of π, allowing it to detect in-plane angle changes from 0 degrees to 180 degrees. Therefore, the tunnel magnetoresistive sensor element determines whether the angle signal falls within the -180-degree to 0-degree range or the 0-degree to 180-degree range, and the planar Hall sensor element then detects the specific angle, thus improving the sensitivity of magnetic angle detection. Furthermore, the four tunnel magnetoresistive sensor elements are uniformly arranged around the planar Hall sensor element, forming a center-ring symmetrical layout. This ensures that each sensor element is in a relatively uniform magnetic field environment, reducing the impact of uneven external magnetic field distribution on the detection results and improving the stability and sensitivity of magnetic angle detection. Furthermore, since the magnetic moment directions of the pinning layers of each tunnel magnetoresistive sensor element are consistent, the response characteristics of each element to changes in the magnetic field are uniform, reducing output errors introduced by differences in device orientation and further improving the reliability and stability of the sensor output signal. In addition, since both planar Hall effect sensors and tunnel magnetoresistive sensors are magnetosensitive conversion elements, the self-induced magnetic field strength they generate during operation has minimal interference with the ambient magnetic field. Therefore, planar Hall effect sensors and tunnel magnetoresistive sensors can be integrated into the same plane (buffer layer), thereby achieving chip flattening.

[0016] The method for preparing the magnetic angle sensor provided by the technical solution of the present invention is used to prepare the above-mentioned magnetic angle sensor, and therefore also has the above-mentioned technical effects, which will not be repeated here. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a technical solution that combines an anisotropic magnetoresistive sensor with a Hall sensor; Figures 2 to 5 This is a schematic diagram of the structure of each step in the preparation method of the magnetic angle sensor provided in the embodiment of the present invention.

[0018] Explanation of reference numerals in the attached figures: 100, Substrate; 110, Insulating layer; 200, Buffer layer; 300, Tunnel magnetoresistive sensor element; 400, Planar Hall sensor element; 410, First electrode; 420, Second electrode. Detailed Implementation

[0019] As mentioned in the background section, improving the sensitivity and stability of magnetic angle sensors are technical problems that need to be solved.

[0020] To address the aforementioned technical problems, the present invention provides a magnetic angle sensor and its fabrication method, which improves the sensitivity and stability of the magnetic angle sensor by integrating a tunnel magnetoresistive sensor and a planar Hall sensor on the same substrate 100.

[0021] To make the above-mentioned objectives, features, and beneficial effects of the present invention more apparent and understandable, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification, claims, and drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus. Additionally, directional terms such as above, below, up, down, upward, downward, left, right, etc., are used relative to exemplary embodiments as they are shown in the figures, with upward or upper directions pointing towards the top of the corresponding figure and downward or lower directions pointing towards the bottom of the corresponding figure.

[0023] Figures 2 to 5 This is a schematic diagram of the structure of each step in the preparation method of the magnetic angle sensor provided in the embodiment of the present invention.

[0024] Please refer to Figure 2 Substrate 100 is provided.

[0025] In this embodiment, the material of the substrate 100 may include Si. The size of the substrate 100 may be 6 inches, 8 inches, 12 inches, etc., and there is no limitation thereto.

[0026] Please refer to Figure 3 A buffer layer 200 is formed on the substrate 100.

[0027] Specifically, the material of the buffer layer 200 may include aluminum oxide.

[0028] In this embodiment, before forming the buffer layer 200, an insulating layer 110 is formed on the surface of the substrate 100.

[0029] Specifically, the buffer layer 200 is located on the surface of the insulating layer 110.

[0030] Specifically, the material of the insulating layer 110 may include silicon dioxide.

[0031] Please refer to Figure 4 Four tunnel magnetoresistive sensor elements 300 are formed on the surface of the buffer layer 200.

[0032] Among them, the magnetic moment directions of the pinning layers of the four tunnel magnetoresistive sensor elements 300 are consistent.

[0033] In this embodiment, the magnetic moment direction of the pinning layer is parallel to the surface of the substrate 100.

[0034] In this embodiment, the method of forming the tunnel magnetoresistive sensor element 300 includes: forming a bottom electrode on the surface of the buffer layer 200; forming a TMR film stack on the surface of the bottom electrode; and forming a top electrode on the surface of the TMR film stack.

[0035] Specifically, the bottom electrode can be made of Au, and the top electrode can also be made of Au.

[0036] In this embodiment, the TMR membrane stack includes a first TMR buffer layer 200, an antiferromagnetic layer, a pinning layer, a barrier layer, a free layer, and a second TMR buffer layer 200 stacked from bottom to top.

[0037] Specifically, the materials of both the first TMR buffer layer 200 and the second TMR buffer layer 200 may include Ta. The first TMR buffer layer 200 can prevent the diffusion of the bottom electrode at high temperatures, and the second TMR buffer layer 200 can prevent the diffusion of the top electrode at high temperatures.

[0038] Specifically, the material of the antiferromagnetic layer can include IrMn.

[0039] Specifically, the pinning layer material can include (Pt,Co)3, and the antiferromagnetic layer fixes the magnetic moment direction of the pinning layer through the exchange bias effect.

[0040] Specifically, the material of the barrier layer can include Al2O3.

[0041] Specifically, the material of the free layer can include (Pt,Co)3, and the magnetic moment of the free layer can change with the external magnetic field.

[0042] Please refer to Figure 5After forming the tunnel magnetoresistive sensor element 300, a planar Hall sensor element 400 is formed on the surface of the buffer layer 200 in the central region of the substrate 100.

[0043] Four tunnel magnetoresistive sensor elements 300 are uniformly arranged around the planar Hall sensor element 400.

[0044] A method for forming a planar Hall sensor 400 element may include: forming a PHE film stack on the surface of a buffer layer 200; forming a first electrode 410 on opposite sides of the PHE film stack, and forming a second electrode 420 on the other opposite sides of the PHE film stack, wherein the extending directions of the first electrode 410 and the extending directions of the second electrode 420 are perpendicular to each other.

[0045] In this embodiment, the PHE membrane stack includes a PHE buffer layer 200, a magnetically sensitive layer, and a PHE protective layer stacked sequentially from bottom to top.

[0046] Specifically, the material of the PHE buffer layer 200 may include Ta.

[0047] Specifically, the material of the magnetically sensitive layer may include Ni. 80 Fe 20 .

[0048] Specifically, the material of the PHE protective layer may include Ta.

[0049] Specifically, the material of the first electrode 410 may include Au, and the material of the second electrode 420 may include Au.

[0050] In other embodiments, the number of tunnel magnetoresistive sensor elements 300 may be more than four, and the more than four tunnel magnetoresistive sensor elements 300 are uniformly surrounded around the sensor element of the planar Hall sensor 400.

[0051] The magnetic angle sensor provided by the technical solution of the present invention, since all four tunnel magnetoresistive sensor elements 300 are located on the surface of the buffer layer 200, and the angular period of the output signal of the tunnel magnetoresistive sensor element 300 changing with the magnetic field direction angle is 2π, can be used to detect in-plane angular changes from -180 degrees to 180 degrees. Since the planar Hall sensor element 400 is located on the surface of the buffer layer 200 in the central region of the substrate 100, and the angular period of the output signal of the planar Hall sensor element 400 changing with the magnetic field direction angle is π, it can be used to detect in-plane angular changes from 0 degrees to 180 degrees. Therefore, by using the tunnel magnetoresistive sensor element 300 to determine whether the angle signal is in the range of -180 degrees to 0 degrees or 0 degrees to 180 degrees, and then using the planar Hall sensor element 400 to detect the specific angle, the sensitivity of magnetic angle detection can be improved. Since the four tunnel magnetoresistive sensor elements 300 are uniformly arranged around the planar Hall sensor element 400, the planar Hall sensor element 400 and the tunnel magnetoresistive sensor element 300 form a center-ring symmetrical layout structure. This allows each sensor element to be in a relatively uniform magnetic field environment, thereby reducing the impact of uneven external magnetic field distribution on the detection results and improving the stability and sensitivity of magnetic angle detection. Furthermore, because the magnetic moment directions of the pinning layers of each tunnel magnetoresistive sensor element 300 are consistent, the response characteristics of each tunnel magnetoresistive sensor element 300 to changes in the magnetic field are consistent, reducing the output error introduced by differences in device orientation and further improving the reliability and stability of the sensor output signal. In addition, since both the planar Hall sensor element 400 and the tunnel magnetoresistive sensor element 300 are magnetosensitive conversion elements, the self-induced magnetic field strength generated during their operation has little interference with the ambient magnetic field. Therefore, the planar Hall sensor element and the tunnel magnetoresistive sensor element 300 can be integrated on the same plane (buffer layer 200), thereby achieving chip flattening.

[0052] Accordingly, this embodiment of the invention also provides a magnetic angle sensor prepared based on the above-described method for preparing a magnetic angle sensor.

[0053] Please continue to refer to this. Figure 5 The magnetic angle sensor includes a substrate 100, a buffer layer 200, four tunnel magnetoresistive sensor elements 300, and a planar Hall sensor element 400.

[0054] Specifically, the buffer layer 200 is located on the substrate 100.

[0055] Specifically, all four tunnel magnetoresistive sensor elements 300 are located on the surface of the buffer layer 200, and the magnetic moment directions of the pinning layers of the four tunnel magnetoresistive sensor elements 300 are consistent.

[0056] In this embodiment, the magnetic moment directions of the pinning layers of the four tunnel magnetoresistive sensor elements 300 are all parallel to the surface of the substrate 100.

[0057] In this embodiment, the tunnel magnetoresistive sensor element 300 includes a bottom electrode, a TMR film stack, and a top electrode stacked from bottom to top.

[0058] Specifically, the planar Hall sensor 400 element is located on the surface of the buffer layer 200 in the central region of the substrate 100, and four tunnel magnetoresistive sensor elements 300 are uniformly surrounded around the planar Hall sensor 400 element.

[0059] In this embodiment, the planar Hall sensor 400 element includes a PHE membrane stack, first electrodes 410 located on opposite sides of the PHE membrane stack, and second electrodes 420 located on the other opposite sides of the PHE membrane stack. The extending directions of the first electrodes 410 and the extending directions of the second electrodes 420 are perpendicular to each other.

[0060] The materials, forming process, working principle, specific implementation method and beneficial effects of the magnetic angle sensor involved in the embodiments of the present invention can be found in the preparation method of the magnetic angle sensor in the embodiments of the present invention, and will not be repeated here.

[0061] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A magnetic angle sensor, characterized in that, include: Substrate; A buffer layer is located on the substrate; Four tunnel magnetoresistive sensor elements are located on the surface of the buffer layer, and the magnetic moment directions of the pinning layers of the four tunnel magnetoresistive sensor elements are consistent. A planar Hall sensor element is located on the surface of a buffer layer in the central region of the substrate, and four tunnel magnetoresistive sensor elements are uniformly surrounding the planar Hall sensor element.

2. The magnetic angle sensor as described in claim 1, characterized in that, The magnetic moment direction of the pinning layer is parallel to the surface of the substrate.

3. The magnetic angle sensor as described in claim 1, characterized in that, The planar Hall sensor element includes a PHE membrane stack, first electrodes located on opposite sides of the PHE membrane stack, and second electrodes located on the other opposite sides of the PHE membrane stack, wherein the extension directions of the first electrodes and the extension directions of the second electrodes are perpendicular to each other.

4. The magnetic angle sensor as described in claim 3, characterized in that, The PHE membrane stack comprises a PHE buffer layer, a magnetically sensitive layer, and a PHE protective layer stacked sequentially from bottom to top.

5. The magnetic angle sensor as described in claim 1, characterized in that, The tunnel magnetoresistive sensor element includes a bottom electrode, a TMR film stack, and a top electrode stacked from bottom to top.

6. The magnetic angle sensor as described in claim 5, characterized in that, The TMR membrane stack comprises, from bottom to top, a first TMR buffer layer, an antiferromagnetic layer, the pinning layer, a barrier layer, a free layer, and a second TMR buffer layer.

7. A method for fabricating a magnetic angle sensor, characterized in that, include: Provide substrate; A buffer layer is formed on the substrate; Four tunnel magnetoresistive sensor elements are formed on the surface of the buffer layer, and the magnetic moment directions of the pinning layers of the four tunnel magnetoresistive sensor elements are consistent. After forming the tunnel magnetoresistive sensor element, a planar Hall sensor element is formed on the surface of the buffer layer in the central region of the substrate, and the four tunnel magnetoresistive sensor elements are uniformly surrounded around the planar Hall sensor element.

8. The method for preparing a magnetic angle sensor as described in claim 7, characterized in that, The method of forming the planar Hall sensor element includes: A PHE film stack is formed on the surface of the buffer layer; A first electrode is formed on each of the opposite sides of the PHE membrane stack, and a second electrode is formed on the other opposite sides of the PHE membrane stack, wherein the extension direction of the first electrode and the extension direction of the second electrode are perpendicular to each other.

9. The method for preparing a magnetic angle sensor as described in claim 7, characterized in that, The method of forming the tunnel magnetoresistive sensor element includes: forming a bottom electrode on the surface of the buffer layer; forming a TMR film stack on the surface of the bottom electrode; and forming a top electrode on the surface of the TMR film stack.

10. The method for preparing a magnetic angle sensor as described in claim 7, characterized in that, Before forming the buffer layer, the method further includes forming an insulating layer on the surface of the substrate.

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