Three-dimensional magnetic field sensor and preparation method thereof

Abstract

The invention relates to a three-dimensional magnetic field sensor and a preparation method thereof. The three-dimensional magnetic field sensor comprises a substrate, an X-axis direction sensor, a Y-axis direction sensor and a Z-axis direction sensor, each of the X-axis direction sensor and the Y-axis direction sensor comprises two anisotropic magnetic resistance strips; the length direction of the anisotropic magnetic resistance strips in the X-axis direction sensor is perpendicular to the length direction of the anisotropic magnetic resistance strips in the Y-axis direction sensor. The Z-axis direction sensor comprises a Hall strip cross structure, and the Hall strip cross structure comprises a buffer layer, an oxidized Pt layer, a thermal annealing Pt layer, a Co layer, an IrMn layer and a protective layer which are sequentially arranged in the direction away from the substrate; the X-axis direction sensor is used for detecting a magnetic field intensity component in the X-axis direction; the Y-axis direction sensor is used for detecting a magnetic field intensity component in the Y-axis direction; the Z-axis direction sensor is used for detecting a magnetic field intensity component in the Z-axis direction; the three-dimensional magnetic field sensor is low in power consumption and wide in range.

Description

Technical Field

[0001] The present application relates to the technical field of magnetic field sensors, and in particular to a three-dimensional magnetic field sensor and a preparation method thereof. Background Art

[0002] With the rapid development of magnetic sensor technology, the demand for the application of magnetic field sensors in aerospace, automotive electronics, intelligent manufacturing and other fields is increasing.

[0003] At present, the mainstream three-dimensional magnetic field sensors in related technologies are mostly based on traditional spin electronics thin film structures, which have many limitations. For example, the driving current is high, resulting in high power consumption, and the measurement range is narrow (about ±2Oe to ±5Oe), which makes it difficult to meet the needs of wide-range magnetic field detection in complex environments. Summary of the Invention

[0004] Based on this, it is necessary to provide a low-power, wide-range three-dimensional magnetic field sensor and a preparation method thereof.

[0005] In a first aspect, the present application provides a three-dimensional magnetic field sensor, comprising: a substrate, and an X-axis direction sensor, a Y-axis direction sensor, and a Z-axis direction sensor spaced apart from each other on the same side of the substrate;

[0006] The X-axis direction sensor and the Y-axis direction sensor each include two anisotropic magnetoresistive strips, and the two anisotropic magnetoresistive strips are arranged side by side and spaced apart;

[0007] The length direction of the anisotropic magnetoresistive strip in the X-axis direction sensor is perpendicular to the length direction of the anisotropic magnetoresistive strip in the Y-axis direction sensor;

[0008] The Z-axis direction sensor includes a Hall bar cross structure, which includes a buffer layer, an oxidized Pt layer, a thermally annealed Pt layer, a Co layer, an IrMn layer, and a protective layer arranged in sequence in a direction away from the substrate; wherein,

[0009] The X-axis direction sensor is used to detect the magnetic field intensity component in the X-axis direction;

[0010] The Y-axis direction sensor is used to detect the magnetic field intensity component in the Y-axis direction;

[0011] The Z-axis direction sensor is used to detect the magnetic field intensity component in the Z-axis direction;

[0012] The Y axis, the X axis, and the Z axis are perpendicular to each other, and the plane where the Y axis and the X axis lie is parallel to the surface of the substrate.

[0013] In one embodiment, the structural parameters of the Hall bar cross structure satisfy at least one of the following:

[0014] The thickness of the Pt oxide layer is (0.2-(0.2×20%))nm to (0.2+(0.2×20%))nm;

[0015] In the process of preparing the Pt oxide layer by using a mixed oxygen sputtering process, the mixed oxygen concentration is 2%;

[0016] The thickness of the IrMn layer is (1-(1×20%))nm to (1+(1×20%))nm;

[0017] The thermal annealing parameters of the thermal annealing Pt layer are annealing at 200° C. for 1 hour;

[0018] The buffer layer is a Ta layer;

[0019] The thickness of the buffer layer is (2-(2×20%))nm to (2+(2×20%))nm;

[0020] The protective layer is a Ta layer;

[0021] The thickness of the protective layer is (3-(3×20%))nm to (3+(3×20%))nm;

[0022] The thickness of the thermally annealed Pt layer before thermal annealing is (2-(2×20%))nm to (2+(2×20%))nm;

[0023] The thickness of the Co layer is 0.8 nm to 0.9 nm;

[0024] The width of the Hall bar is (75-(75×20%)) μm to (75+(75×20%)) μm.

[0025] In one embodiment, the Z-axis direction sensor further includes four electrodes;

[0026] The four electrodes are respectively connected to the four ends of the Hall bar cross structure.

[0027] In one embodiment, the anisotropic magnetoresistive strip includes a buffer layer, a NiFe layer, and a protective layer sequentially arranged in a direction away from the substrate.

[0028] In one embodiment, the thickness of the NiFe layer is (45-(45×20%))nm to (45+(45×20%))nm;

[0029] The width of the anisotropic magnetoresistive strip is (80-(80×20%)) μm to (80+(80×20%)) μm.

[0030] In one embodiment, the X-axis direction sensor and the Y-axis direction sensor each further include four Babe electrodes; and in at least one of the X-axis direction sensor and the Y-axis direction sensor:

[0031] The first Babe electrode is connected to the first ends of the two anisotropic magnetoresistive strips, the second Babe electrode is connected to the second ends of the two anisotropic magnetoresistive strips, the third Babe electrode is connected to the middle part of one of the two anisotropic magnetoresistive strips, and the fourth Babe electrode is connected to the middle part of the other of the two anisotropic magnetoresistive strips.

[0032] In one embodiment, the structural parameters of the four Babe electrodes satisfy at least one of the following:

[0033] The width of each of the Babe electrodes is (8-(8×20%)) μm to (8+(8×20%)) μm;

[0034] The gap between two adjacent Babe electrodes is (8-(8×20%)) μm to (8+(8×20%)) μm.

[0035] In a second aspect, based on the same inventive concept, the present application also provides a method for preparing a three-dimensional magnetic field sensor, comprising:

[0036] providing a substrate;

[0037] An X-axis direction sensor, a Y-axis direction sensor, and a Z-axis direction sensor are formed on the same side of the substrate and spaced apart from each other; wherein,

[0038] The X-axis direction sensor and the Y-axis direction sensor each include two anisotropic magnetoresistive strips, and the two anisotropic magnetoresistive strips are arranged side by side and spaced apart;

[0039] The length direction of the anisotropic magnetoresistive strip in the X-axis direction sensor is perpendicular to the length direction of the anisotropic magnetoresistive strip in the Y-axis direction sensor;

[0040] The Z-axis direction sensor includes a Hall bar cross structure, and the Hall bar cross structure includes a buffer layer, an oxidized Pt layer, a thermally annealed Pt layer, a Co layer, an IrMn layer, and a protective layer arranged in sequence in a direction away from the substrate;

[0041] The X-axis direction sensor is used to detect the magnetic field intensity component in the X-axis direction;

[0042] The Y-axis direction sensor is used to detect the magnetic field intensity component in the Y-axis direction;

[0043] The Z-axis direction sensor is used to detect the magnetic field intensity component in the Z-axis direction;

[0044] The Y axis, the X axis, and the Z axis are perpendicular to each other, and the plane where the Y axis and the X axis lie is parallel to the surface of the substrate.

[0045] In one embodiment, forming the Z-axis direction sensor includes:

[0046] Sputtering a Ta layer with a thickness of 2 nm on one side of the substrate as the buffer layer;

[0047] Using a mixed oxygen sputtering process, a Pt oxide layer with a thickness of 0.2 nm is prepared on the side of the buffer layer away from the substrate, wherein the mixed oxygen concentration is 2%;

[0048] Depositing the Pt layer with a thickness of 2 nm on a side of the Pt oxide layer away from the substrate to obtain a base sample;

[0049] Annealing the basic sample at 200° C. for 1 h to obtain an annealed sample;

[0050] Depositing the Co layer with a thickness of 0.8 nm to 0.9 nm on the side of the Pt layer away from the substrate in the annealed sample;

[0051] forming the IrMn layer with a thickness of 1 nm on a side of the Co layer away from the substrate;

[0052] sputtering a Ta layer with a thickness of 3 nm on a side of the IrMn layer away from the substrate as the protective layer to obtain an initial sample;

[0053] Processing the initial sample into the Hall bar cross structure with a Hall bar width of 75 μm by using a photolithography process and an etching process;

[0054] Four electrodes are prepared by electron beam deposition, and the four electrodes are respectively connected to the four ends of the Hall bar cross structure.

[0055] In one embodiment, the anisotropic magnetoresistive strip includes a buffer layer, a NiFe layer, and a protective layer sequentially arranged in a direction away from the substrate; forming the X-axis direction sensor or the Y-axis direction sensor includes:

[0056] sputtering a Ta layer on one side of the substrate as a buffer layer in the anisotropic magnetoresistive strip;

[0057] Sputtering a NiFe layer with a thickness of 45 nm on a side of the buffer layer in the anisotropic magnetoresistive strip away from the substrate;

[0058] sputtering a Ta layer on a side of the NiFe layer away from the substrate as a protective layer in the anisotropic magnetoresistive strip to obtain an original sample;

[0059] Processing the original sample into the anisotropic magnetoresistive strip with a width of 80 μm by using a photolithography process and an etching process;

[0060] A Babe electrode is prepared, and the Babe electrode is connected to the corresponding anisotropic magnetoresistive strip.

[0061] In the above-mentioned three-dimensional magnetic field sensor and its preparation method, the X-axis direction sensor and the Y-axis direction sensor are respectively an anisotropic magnetoresistive (AMR) sensor in the X-axis direction and an anisotropic magnetoresistive (AMR) sensor in the Y-axis direction, which are used to respectively realize the detection of the magnetic field intensity component in the X-axis direction and the magnetic field intensity component in the Y-axis direction within the plane. Experimental test results show that the anisotropic magnetoresistive sensor in the embodiment of the present application has a range of up to ±1.9Oe, and has stable performance and a sensitivity of 25V / A / T. On this basis, the Z-axis direction sensor is an anomalous Hall effect (AHE) sensor in the Z-axis direction, which is used to realize the detection of the magnetic field intensity component in the out-of-plane Z-axis direction. Among them, by optimizing the arrangement of the buffer layer, the oxidized Pt layer, the thermally annealed Pt layer, the Co layer, the IrMn layer and the protective layer, the experimental test results show that the coercive field of the AHE sensor is significantly reduced, the range can be extended to ±20Oe, the minimum excitation current is reduced to 10μA, and the performance is stable, maintaining a high sensitivity of approximately 6000V / A / T; the embodiment of the present application thus realizes a low-power, wide-range three-dimensional magnetic field sensor.

[0062] In other words, the embodiments of the present application effectively improve the spin-orbit coupling at the Pt / Co interface and reduce the coercive field by regulating the oxidation of the Pt layer, regulating the exchange bias of the thin IrMn layer, thermal annealing of the Pt layer, and optimizing the buffer layer and protective layer. At the same time, it significantly improves the magnetic field range of the out-of-plane AHE sensor and reduces the power consumption of the sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the following briefly introduces the drawings required for use in the embodiments or the conventional technology descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0064] Figure 1 A microscope photograph of a three-dimensional magnetic field sensor according to an embodiment;

[0065] Figure 1a for Figure 1 Black and white picture;

[0066] Figure 2 A schematic diagram of the film structure of a Hall bar cross structure according to an embodiment;

[0067] Figure 3 Schematic diagram of the film structure of an anisotropic magnetoresistive strip according to one embodiment;

[0068] Figure 4 A mask design diagram of an embodiment;

[0069] Figure 4a for Figure 4 Black and white picture;

[0070] Figure 5 This is a diagram of AHE sensor test data according to an embodiment;

[0071] Figure 5a for Figure 5 Black and white picture. DETAILED DESCRIPTION

[0072] To facilitate understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The accompanying drawings provide embodiments of the present application. However, the present application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0073] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0074] It will be understood that the terms "first," "second," etc., used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor without departing from the scope of this application. The first resistor and the second resistor are both resistors, but they are not the same resistor.

[0075] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if there is transmission of electrical signals or data between the connected circuits, modules, units, etc.

[0076] It is understood that “at least one” refers to one or more, “a plurality” refers to two or more, and “at least a portion of an element” refers to a portion or all of an element.

[0077] As used herein, the singular forms "a," "an," and "the" may also include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include," "comprising," "having," and the like specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. Furthermore, the term "and / or" as used in this specification includes any and all combinations of the relevant listed items.

[0078] In an exemplary embodiment, referring to Figure 1 , provides a three-dimensional magnetic field sensor, which includes a substrate 10 and an X-axis direction sensor 20, a Y-axis direction sensor 30 and a Z-axis direction sensor 40 arranged at intervals on the same side of the substrate 10.

[0079] The substrate 10 is, for example but not limited to, a Si / SiO 2 substrate. The Y axis, X axis, and Z axis are perpendicular to each other, and the plane where the Y axis and X axis lie is parallel to the surface of the substrate 10 .

[0080] The X-axis direction sensor 20 and the Y-axis direction sensor 30 each include two anisotropic magnetoresistive strips 50 , so that the X-axis direction sensor 20 and the Y-axis direction sensor 30 are an anisotropic magnetoresistive (AMR) sensor in the X-axis direction and an AMR sensor in the Y-axis direction, respectively.

[0081] In the X-axis AMR sensor, two anisotropic magnetoresistive strips 50 are arranged side by side and spaced apart. In the Y-axis AMR sensor, two anisotropic magnetoresistive strips 50 are arranged side by side and spaced apart. The length direction of the anisotropic magnetoresistive strips 50 in the X-axis sensor 20 is perpendicular to the length direction of the anisotropic magnetoresistive strips 50 in the Y-axis sensor 30.

[0082] The X-axis direction sensor 20 is used to detect the magnetic field strength component in the X-axis direction, and the Y-axis direction sensor 30 is used to detect the magnetic field strength component in the Y-axis direction. That is, the X-axis direction AMR sensor and the Y-axis direction AMR sensor are used to respectively realize the detection of the magnetic field strength component in the X-axis direction and the magnetic field strength component in the Y-axis direction within the plane.

[0083] The Z-axis direction sensor 40 includes a Hall bar cross structure 60 , so that the Z-axis direction sensor 40 is an anomalous Hall Effect (AHE) sensor in the Z-axis direction. The Z-axis AHE sensor is used to detect the out-of-plane magnetic field intensity component in the Z-axis direction.

[0084] refer to Figure 2 The Hall bar cross structure 60 includes a buffer layer, an oxidized Pt layer, a thermally annealed Pt layer (ie, Figure 2 The Pt layer is shown in FIG, wherein the Pt oxide layer is prepared by mixed oxygen sputtering. The thermal annealing of the Pt layer is carried out by Figure 2 The Pt layer shown in the figure is thermally annealed. IrMn is an antiferromagnetic (AFM) material; after the IrMn layer forms an interface with the Co layer, an exchange bias effect can be generated.

[0085] In the embodiment of the present application, the X-axis direction sensor 20, the Y-axis direction sensor 30 and the Z-axis direction sensor 40 can independently detect the magnetic field intensity components in the X-axis direction, the Y-axis direction and the Z-axis direction, respectively. In other words, the X-axis direction sensor 20 can independently measure the magnetic field intensity component in the X-axis direction, the Y-axis direction sensor 30 can independently measure the magnetic field intensity component in the Y-axis direction, and the Z-axis direction sensor 40 can independently measure the magnetic field intensity component in the Y-axis direction.

[0086] The Pt layer is thermally annealed to optimize its crystal structure and interface quality. An IrMn layer is introduced into the Pt / Co system, leveraging the Co / IrMn exchange bias effect to enhance the system's perpendicular magnetic anisotropy (PMA). Simultaneously, an oxidized Pt layer is introduced to further enhance the system's PMA properties. This reduces the coercive field of the Z-axis AHE sensor, broadens the measurement range of the Z-axis AHE sensor, reduces the excitation current of the Z-axis AHE sensor, and improves the stability and sensitivity of the Z-axis AHE sensor.

[0087] The experimental test results show that the range of the AMR in the embodiment of the present application can reach ±1.9Oe, and the performance is stable, the sensitivity is 25V / A / T, and the resistance is about 65Ω; on this basis, the reference Figure 5 The coercive field of the AHE sensor is significantly reduced (for example, it can be reduced to 1Oe), the range is extended to ±20Oe, the minimum excitation current is reduced to 10μA, and the performance is stable, maintaining a high sensitivity of 6141V / A / T; the embodiment of the present application thus realizes a low-power, wide-range three-dimensional magnetic field sensor.

[0088] The embodiments of the present application break through the range bottleneck of traditional magnetic field sensors by optimizing the magnetic film structure and sensor design, enabling it to maintain stable and linear measurement performance within a wider range of magnetic field strengths, thereby meeting the needs of industrial manufacturing, medical diagnosis, aerospace, and precision measurement. Systematic improvements are made in material selection, device design optimization, and other aspects to reduce the energy consumption of the sensor when it is working, thereby improving the endurance of the equipment and making it suitable for long-term, low-power operation scenarios. In terms of high sensitivity, one of the core performance of a magnetic field sensor is the ability to detect extremely weak magnetic field signals. In order to improve sensitivity, the embodiments of the present application precisely control the microstructure of the magnetic film, optimize the interlayer coupling, and improve the micromachining process to reduce noise and improve signal response, thereby achieving higher magnetic field detection accuracy, enabling it to provide high-resolution measurement results in a weak magnetic environment.

[0089] Because the performance, PMA characteristics, and exchange bias effect of an AHE sensor are highly sensitive to the fabrication parameters of the AHE sensor and the physical parameters and dimensions of each film layer, the inventors of the present application have determined that, in an exemplary embodiment, the AHE sensor and the three-dimensional magnetic field sensor can achieve target performance, target PMA characteristics, and target exchange bias effect when the structural parameters of the Hall bar cross structure 60 satisfy at least one of the following conditions:

[0090] The thickness of the Pt oxide layer is (0.2-(0.2×20%))nm to (0.2+(0.2×20%))nm; in the preparation process of the Pt oxide layer using a mixed oxygen sputtering process, the mixed oxygen concentration is 2%; the thickness of the IrMn layer is (1-(1×20%))nm to (1+(1×20%))nm; the thermal annealing parameters of the thermally annealed Pt layer are annealing at 200°C for 1h; the buffer layer is a Ta layer; the thickness of the buffer layer is (2-(2×20%)) nm~(2+(2×20%))nm; the protective layer is a Ta layer; the thickness of the protective layer is (3-(3×20%))nm~(3+(3×20%))nm; the thickness of the thermally annealed Pt layer before thermal annealing is (2-(2×20%))nm~(2+(2×20%))nm; the thickness of the Co layer is 0.8nm~0.9nm; the width of the Hall bar is (75-(75×20%))μm~(75+(75×20%))μm.

[0091] Exemplarily, the thickness of the Pt oxide layer is 0.2 nm; in the preparation process of the Pt oxide layer using a mixed oxygen sputtering process, the mixed oxygen concentration is 2%; the thickness of the IrMn layer is 1 nm; the thermal annealing parameters of the thermally annealed Pt layer are annealing at 200°C for 1 h; the buffer layer is a Ta layer; the thickness of the buffer layer is 2 nm; the protective layer is a Ta layer; the thickness of the protective layer is 3 nm; the thickness of the thermally annealed Pt layer before thermal annealing is 2 nm; the thickness of the Co layer is 0.8 nm to 0.9 nm; and the width of the Hall bar is 75 μm.

[0092] By adding an IrMn film to the Pt / Co film, an exchange bias effect was introduced into the original PMA system, and a PMA film with a Pt / Co / IrMn structure was prepared. By varying the thickness of the IrMn layer, the effect of IrMn on the PMA of the Pt / Co system was studied. Pt / Co / IrMn Hall bar samples with different IrMn layer thicknesses were prepared and magnetoresistance measurements were performed. The test results show that the introduction of the IrMn layer can effectively increase the range of the AHE sensor. Compared with the PMA film with a Pt / Co / structure, the introduction of IrMn into the Pt / Co system can induce a significant exchange bias field through interfacial exchange coupling, thereby enhancing the PMA characteristics of the system.

[0093] Annealing is a method that uses heat treatment to cause atomic rearrangement within a thin film, release internal stress, and improve the interface structure. In this embodiment of the present application, the effect of Pt layer annealing on the performance of a Pt / Co AHE sensor was studied. During the preparation of a Pt / Co structured thin film by magnetron sputtering, after the Pt layer film is prepared, the film temperature is heated to 200°C and annealed for about 1 hour. After annealing, the temperature in the magnetron chamber is allowed to drop to room temperature before magnetron sputtering of the Co film is continued. Magnetoresistance testing was performed on the prepared samples, and it was found that annealing the Pt layer can effectively improve sensitivity.

[0094] The effect of oxygen atomic diffusion on the perpendicular magnetic anisotropy of a Pt / Co structure was studied. The core mechanism by which the Pt / Co structure can produce perpendicular magnetic anisotropy lies in the spin-orbit coupling effect between the Co layer and the Pt layer. By introducing an appropriate amount of oxygen during the magnetron sputtering process, a Pt oxide film was successfully prepared, and on this basis, an oxidized Pt / Pt / Co multilayer film structure was constructed. Experimental results show that the introduction of the Pt oxide layer can effectively regulate the magnetic and electrical transport properties of the film, thereby significantly broadening the measurement range of the magnetic field sensor. In addition, this method provides a wider parameter window during the film preparation process, improving the controllability of the process and the stability of production.

[0095] Theoretically, the diffusion of an appropriate amount of oxygen atoms can improve interface quality and moderately enhance magnetic anisotropy. However, excessive oxygen diffusion can lead to excessive oxidation of the Pt / Co interface, thereby disrupting the magnetic coupling required for PMA generation. Therefore, controlling the oxygen mixing parameters in this experiment is crucial. The results demonstrate that introducing a 0.2nm thick Pt oxide layer at a 2% mixed oxygen concentration can both stabilize the Pt / Co interface and extend the device's measurement range.

[0096] Substrates with varying thermal conductivity, such as Kapton and photoresist, were studied. Using a substrate with poor thermal conductivity exploits the thermal effect of current flow. When current is passed, heat accumulates at the interface between the substrate and the film. This accumulated heat is used to compensate for the free energy required for control, thereby reducing the drive current density. The study found that using a substrate with poor thermal conductivity can significantly reduce the power consumption of the AHE device.

[0097] Tantalum (Ta) was chosen as the buffer and protective layer material for the thin-film device, primarily due to its widespread application and mature processing conditions in our laboratory. Compared to other potential candidate materials, the use of Ta improves experimental controllability and reproducibility, thereby simplifying the preparation process.

[0098] In an exemplary embodiment, referring to Figure 1 The Z-axis direction sensor 40 also includes four electrodes 80, which are, for example but not limited to, Babe electrodes. The material of the electrode can be Au / Ti. The four electrodes 80 are respectively connected to the four ends of the Hall bar cross structure 60; two electrodes 80 are used to connect to the external excitation current end for receiving the excitation current provided by the external excitation current end, and the other two electrodes 80 are used to connect to the external voltage test end for outputting a voltage signal to the external voltage test end. After the excitation current is input to the Z-axis direction sensor 40, the magnetic field intensity component in the Z-axis direction can be inversely calculated based on the output voltage of the Z-axis direction sensor 40. The three-dimensional magnetic field intensity can be obtained by vector synthesis of the magnetic field intensity component in the Z-axis direction, the magnetic field intensity component in the Y-axis direction, and the magnetic field intensity component in the X-axis direction.

[0099] In an exemplary embodiment, referring to Figure 3 The anisotropic magnetoresistive strip 50 includes a buffer layer, a NiFe layer (ie Figure 3 The buffer layer and the protective layer can both be Ta layers. The buffer layer also has the function of improving the adhesion between the film layers.

[0100] In an exemplary embodiment, referring to Figure 3 The thickness of the NiFe layer is (45-(45×20%))nm to (45+(45×20%))nm. Exemplarily, the thickness of the NiFe layer is 45nm.

[0101] In an exemplary embodiment, referring to Figure 1 The width of the anisotropic magnetoresistive strip 50 is (80-(80×20%)) μm to (80+(80×20%)), and the exemplary width of the anisotropic magnetoresistive strip 50 is 80 μm.

[0102] In an exemplary embodiment, referring to Figure 1 The X-axis direction sensor 20 and the Y-axis direction sensor 30 also include four Babe electrodes 70 .

[0103] refer to Figure 1 , the following settings are satisfied in at least one of the X-axis direction sensor 20 and the Y-axis direction sensor 30:

[0104] The first Babe electrode 70 is connected to the first ends of both anisotropic magnetoresistive strips 50, the second Babe electrode 70 is connected to the second ends of both anisotropic magnetoresistive strips 50, the third Babe electrode 70 is connected to the middle portion of one of the two anisotropic magnetoresistive strips 50, and the fourth Babe electrode 70 is connected to the middle portion of the other of the two anisotropic magnetoresistive strips 50. The first and second Babe electrodes 70 are connected to external excitation current terminals, while the third and fourth Babe electrodes 70 are connected to external voltage test terminals. After the excitation current is input to the Y-axis direction sensor 30, the Y-axis magnetic field intensity component can be inversely calculated based on the output voltage of the Y-axis direction sensor 30. After the excitation current is input to the X-axis direction sensor 20, the X-axis magnetic field intensity component can be inversely calculated based on the output voltage of the X-axis direction sensor 20.

[0105] In an exemplary embodiment, the structural parameters of the four Babe electrodes 70 satisfy at least one of the following:

[0106] Each of the Babe electrodes 70 has a width of 8 μm, and the gap between two adjacent Babe electrodes 70 is 8 μm. Alternatively, the width of the Babe electrodes 70 may range from (8-(8×20%)) μm to (8+(8×20%)) μm, and the gap between two adjacent Babe electrodes 70 may range from (8-(8×20%)) μm to (8+(8×20%)) μm.

[0107] This embodiment uses two orthogonally placed AMR sensors with NiFe barbeque electrodes to measure a ±1.8 Oe two-dimensional magnetic field in the in-plane direction. Using micro-nanofabrication, the AMR sensor and two AMR sensors are fabricated onto a square silicon wafer. The resulting three-dimensional magnetic field sensor measures 4 mm x 4 mm, significantly reducing its size.

[0108] The present application also provides a method for preparing a three-dimensional magnetic field sensor. The method can be used to prepare the three-dimensional magnetic field sensor in any of the above embodiments. The method includes:

[0109] S102, providing a substrate.

[0110] S104, forming an X-axis direction sensor, a Y-axis direction sensor and a Z-axis direction sensor spaced apart from each other on the same side of the substrate; wherein,

[0111] The X-axis direction sensor and the Y-axis direction sensor each include two anisotropic magnetoresistive strips, which are arranged side by side and spaced apart.

[0112] The length direction of the anisotropic magnetoresistive strip in the X-axis direction sensor is perpendicular to the length direction of the anisotropic magnetoresistive strip in the Y-axis direction sensor;

[0113] The Z-axis direction sensor includes a Hall bar cross structure, which includes a buffer layer, an oxidized Pt layer, a thermally annealed Pt layer, a Co layer, an IrMn layer, and a protective layer arranged in sequence in a direction away from the substrate;

[0114] X-axis direction sensor, used to detect the magnetic field intensity component in the X-axis direction;

[0115] Y-axis direction sensor, used to detect the magnetic field intensity component in the Y-axis direction;

[0116] Z-axis direction sensor, used to detect the magnetic field intensity component in the Z-axis direction;

[0117] The Y axis, the X axis, and the Z axis are perpendicular to each other, and the plane where the Y axis and the X axis lie is parallel to the surface of the substrate.

[0118] In an exemplary embodiment, forming the Z-axis direction sensor in S104 includes:

[0119] S1101: Sputter a 2 nm thick Ta layer on one side of the substrate as a buffer layer in the Hall bar cross structure. The Ta layer may be prepared by magnetron sputtering.

[0120] S1102 , using a mixed oxygen sputtering process, a Pt oxide layer with a thickness of 0.2 nm is prepared on a side of the buffer layer away from the substrate, wherein the mixed oxygen concentration is 2%.

[0121] The introduction of the Pt oxide layer effectively optimizes the PMA effect by regulating the spin-orbit coupling and magnetic domain structure at the Pt / Co interface, thereby enabling the device to maintain a stable magnetoresistance response over a wide range of applied magnetic fields. The inclusion of the oxide layer not only facilitates the preparation of PMA films with a low coercive field and high yield, but also provides solid technical support for the low-power and high-performance applications of anomalous Hall effect sensors by extending the device's magnetic field range (increased by approximately 17%).

[0122] In step S1103, a 2 nm thick Pt layer is deposited on the side of the oxidized Pt layer away from the substrate to obtain a base sample. The uniformly deposited Pt thin film serves as a substrate for the subsequent deposition of the Co layer, providing excellent electrical conductivity and also modulating the magnetic properties of the Co layer to a certain extent, for example, enhancing the magnetic properties of the Co layer.

[0123] S1104, annealing the base sample at 200°C for 1 hour to obtain an annealed sample.

[0124] Specifically, annealing can be performed at 200°C ± 10°C for approximately 1 hour. The substrate temperature is rapidly raised to 200°C, where annealing is performed for 1 hour. This annealing step is intended to promote atomic rearrangement within the Pt layer, optimize the crystal structure, reduce interface roughness, and effectively release internal stress generated during deposition, thereby creating more ideal interface conditions for subsequent Co layer deposition.

[0125] Thermal annealing helps to improve the crystal structure and interface quality of the Pt layer. During the thermal annealing process, the atoms in the Pt layer obtain enough energy to rearrange, thereby reducing the interface roughness and internal defects and reducing stress concentration. This not only increases the grain size of the Pt layer and reduces the grain boundaries, but also provides a more uniform and continuous substrate for the subsequent deposition of the Co layer. This optimization effect helps to enhance the magnetic uniformity of the Co layer and increase its saturation magnetization (Ms). The saturation magnetization is closely related to the volume magnetic moment of the magnetic material, and its improvement directly improves the response accuracy of the device under weak magnetic fields. Furthermore, after the Co layer obtains a higher Ms, the energy barrier in its magnetization process will be increased accordingly, making the magnetization reversal process smoother and reducing the coercive field (Hc). According to the theory of magnetic anisotropy, the reduction of the coercive field means that the interaction between magnetic domains in the film tends to be uniform, and the energy loss during magnetization reversal is reduced.

[0126] Furthermore, from a spintronics perspective, the annealing process improves the spin-orbit coupling efficiency at the Pt / Co interface, which is crucial for the formation and maintenance of perpendicular magnetic anisotropy. This enhanced spin-orbit coupling results in more uniform domain wall movement, further reducing the asymmetry and noise level of the hysteresis loop. This combination of effects ultimately leads to higher magnetoresistance change rates and improved sensing performance in electrical testing of the annealed samples.

[0127] In summary, the thermal annealing process plays a key role in optimizing the structure of magnetic films, specifically in the following aspects: First, through appropriate temperature control, it can effectively release the internal stress generated in the film during deposition, promote the rearrangement of the internal lattice of the Pt layer and the uniformity of the grain size, thereby significantly improving the crystal quality and surface smoothness of the Pt layer. This change not only reduces the density of grain boundary defects but also provides a more ideal growth template for the subsequent deposition of the Co layer, helping to form a continuous and dense ferromagnetic layer structure.

[0128] Secondly, as the quality of the Pt / Co interface structure improves, the spin-orbit coupling effect is also enhanced, thereby strengthening the stability of the perpendicular magnetic anisotropy. This improvement in the spintronic properties of the interface further enhances carrier spin polarization and transmission efficiency, laying the physical foundation for the enhancement of the anomalous Hall effect. In terms of macroscopic performance, the annealed samples exhibit steeper and squarer hysteresis loops, significantly reduced coercive fields, and a smoother and more controllable magnetization reversal process, demonstrating improved magnetic domain structural uniformity.

[0129] More importantly, experimental data showed that the annealed sample exhibited a significant increase in magnetoresistance change rate, boosting sensor sensitivity by over 26%. This significantly enhances the sensor's responsiveness in weak magnetic field detection. Furthermore, the improved magnetic uniformity after annealing allows for a stable magnetoresistance signal at lower excitation currents, effectively reducing device power consumption.

[0130] S1105, depositing a Co layer with a thickness of 0.8 nm to 0.9 nm on the side of the Pt layer in the annealed sample away from the substrate, wherein the Co layer may be formed by magnetron sputtering.

[0131] S1106 , forming an IrMn layer with a thickness of 1 nm on a side of the Co layer away from the substrate.

[0132] S1107 , sputtering a Ta layer with a thickness of 3 nm on the side of the IrMn layer away from the substrate as a protective layer in the Hall bar cross structure to obtain an initial sample.

[0133] S1108 , using a photolithography process and an etching process, processing the initial sample into a Hall bar cross structure with a Hall bar width of 75 μm.

[0134] S1109, preparing four electrodes by electron beam deposition, and connecting the four electrodes to the four ends of the Hall bar cross structure respectively.

[0135] In an exemplary embodiment, the anisotropic magnetoresistive strip includes a buffer layer, a NiFe layer, and a protective layer sequentially arranged in a direction away from the substrate. Forming the X-axis direction sensor in S104 or forming the Y-axis direction sensor in S104 includes:

[0136] S1201 , sputtering a Ta layer on one side of the substrate as a buffer layer in the anisotropic magnetoresistive strip.

[0137] S1202 , sputtering a NiFe layer with a thickness of 45 nm on a side of the buffer layer in the anisotropic magnetoresistive strip away from the substrate.

[0138] S1203, sputtering a Ta layer on the side of the NiFe layer away from the substrate as a protective layer in the anisotropic magnetoresistive strip to obtain an original sample.

[0139] S1204, using a photolithography process and an etching process, the original sample is processed into an anisotropic magnetoresistive strip with a width of 80 μm.

[0140] S1205, preparing a Babe electrode and connecting the Babe electrode to the corresponding anisotropic magnetoresistive strip.

[0141] In an exemplary embodiment, the mask is designed as Figure 4 As shown, the prepared out-of-plane AHE sensor and the two prepared in-plane AMR sensors are integrated according to a predetermined layout to form a complete three-dimensional magnetic field sensing system to achieve all-round magnetic field measurement; finally, the three-dimensional magnetic field sensing system can be set on a base and packaged to form a three-dimensional magnetic field sensor product.

[0142] The three-dimensional magnetic field sensor and the method for preparing the three-dimensional magnetic field sensor provided in the embodiments of the present application belong to the same inventive concept, can solve the same technical problem, and thus achieve the same technical effect, and repeated contents will not be repeated.

[0143] In this embodiment, the three-dimensional magnetic field measurement is split into two components: in-plane (XY direction) and out-of-plane (Z direction). The in-plane magnetic field component is measured using two orthogonally placed anisotropic magnetoresistive (AMR) sensors, while the out-of-plane magnetic field is measured using an anomalous Hall effect (AHE) sensor. Furthermore, the deposition of each film layer in this embodiment can be performed using a magnetron sputtering process. Standard photolithography processes can be used for micro- and nano-fabrication of the sample.

[0144] The following are the materials used in the embodiments of the present application: Ta (tantalum), Pt (platinum), Co (cobalt), IrMn (iridium manganese), Si (silicon), SiO2 (silicon dioxide), NiFe (Permalloy), Au (gold), and Ti (titanium).

[0145] In the description of this specification, reference to the terms "some embodiments" or "other embodiments" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example.

[0146] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0147] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

Claims

1. A three-dimensional magnetic field sensor, characterized in that: include: A substrate and an X-axis direction sensor, a Y-axis direction sensor, and a Z-axis direction sensor spaced apart from each other on the same side of the substrate; The X-axis direction sensor and the Y-axis direction sensor each include two anisotropic magnetoresistive strips, and the two anisotropic magnetoresistive strips are arranged side by side and spaced apart; The length direction of the anisotropic magnetoresistive strip in the X-axis direction sensor is perpendicular to the length direction of the anisotropic magnetoresistive strip in the Y-axis direction sensor; The Z-axis direction sensor includes a Hall bar cross structure, which includes a buffer layer, an oxidized Pt layer, a thermally annealed Pt layer, a Co layer, an IrMn layer, and a protective layer arranged in sequence in a direction away from the substrate; wherein, The X-axis direction sensor is used to detect the magnetic field intensity component in the X-axis direction; The Y-axis direction sensor is used to detect the magnetic field intensity component in the Y-axis direction; The Z-axis direction sensor is used to detect the magnetic field intensity component in the Z-axis direction; The Y axis, the X axis, and the Z axis are perpendicular to each other, and the plane where the Y axis and the X axis lie is parallel to the surface of the substrate.

2. The three-dimensional magnetic field sensor according to claim 1, characterized in that The structural parameters of the Hall bar cross structure satisfy at least one of the following: The thickness of the Pt oxide layer is (0.2-(0.2×20%))nm to (0.2+(0.2×20%))nm; In the process of preparing the Pt oxide layer by using a mixed oxygen sputtering process, the mixed oxygen concentration is 2%; The thickness of the IrMn layer is (1-(1×20%))nm to (1+(1×20%))nm; The thermal annealing parameters of the thermal annealing Pt layer are annealing at 200° C. for 1 hour; The buffer layer is a Ta layer; The thickness of the buffer layer is (2-(2×20%))nm to (2+(2×20%))nm; The protective layer is a Ta layer; The thickness of the protective layer is (3-(3×20%))nm to (3+(3×20%))nm; The thickness of the thermally annealed Pt layer before thermal annealing is (2-(2×20%))nm to (2+(2×20%))nm; The thickness of the Co layer is 0.8 nm to 0.9 nm; The width of the Hall bar is (75-(75×20%)) μm to (75+(75×20%)) μm.

3. The three-dimensional magnetic field sensor according to claim 1, characterized in that The Z-axis direction sensor also includes four electrodes; The four electrodes are respectively connected to the four ends of the Hall bar cross structure.

4. The three-dimensional magnetic field sensor according to claim 1, characterized in that The anisotropic magnetoresistive strip includes a buffer layer, a NiFe layer and a protective layer which are sequentially arranged in a direction away from the substrate.

5. The three-dimensional magnetic field sensor according to claim 4, characterized in that: The thickness of the NiFe layer is (45-(45×20%))nm to (45+(45×20%))nm; The width of the anisotropic magnetoresistive strip is (80-(80×20%)) μm to (80+(80×20%)) μm.

6. The three-dimensional magnetic field sensor according to claim 1, characterized in that: The X-axis direction sensor and the Y-axis direction sensor each further include four Babe electrodes; and in at least one of the X-axis direction sensor and the Y-axis direction sensor: The first Babe electrode is connected to the first ends of the two anisotropic magnetoresistive strips, the second Babe electrode is connected to the second ends of the two anisotropic magnetoresistive strips, the third Babe electrode is connected to the middle part of one of the two anisotropic magnetoresistive strips, and the fourth Babe electrode is connected to the middle part of the other of the two anisotropic magnetoresistive strips.

7. The three-dimensional magnetic field sensor according to claim 6, characterized in that: The structural parameters of the four Babe electrodes satisfy at least one of the following: The width of each of the Babe electrodes is (8-(8×20%)) μm to (8+(8×20%)) μm; The gap between two adjacent Babe electrodes is (8-(8×20%)) μm to (8+(8×20%)) μm.

8. A method for preparing a three-dimensional magnetic field sensor, characterized in that: include: providing a substrate; An X-axis direction sensor, a Y-axis direction sensor, and a Z-axis direction sensor are formed on the same side of the substrate and spaced apart from each other; wherein, The X-axis direction sensor and the Y-axis direction sensor each include two anisotropic magnetoresistive strips, and the two anisotropic magnetoresistive strips are arranged side by side and spaced apart; The length direction of the anisotropic magnetoresistive strip in the X-axis direction sensor is perpendicular to the length direction of the anisotropic magnetoresistive strip in the Y-axis direction sensor; The Z-axis direction sensor includes a Hall bar cross structure, and the Hall bar cross structure includes a buffer layer, an oxidized Pt layer, a thermally annealed Pt layer, a Co layer, an IrMn layer, and a protective layer arranged in sequence in a direction away from the substrate; The X-axis direction sensor is used to detect the magnetic field intensity component in the X-axis direction; The Y-axis direction sensor is used to detect the magnetic field intensity component in the Y-axis direction; The Z-axis direction sensor is used to detect the magnetic field intensity component in the Z-axis direction; The Y axis, the X axis, and the Z axis are perpendicular to each other, and the plane where the Y axis and the X axis lie is parallel to the surface of the substrate.

9. The method according to claim 8, characterized in that The Z-axis direction sensor is formed, including: Sputtering a Ta layer with a thickness of 2 nm on one side of the substrate as the buffer layer; Using a mixed oxygen sputtering process, a Pt oxide layer with a thickness of 0.2 nm is prepared on the side of the buffer layer away from the substrate, wherein the mixed oxygen concentration is 2%; Depositing the Pt layer with a thickness of 2 nm on a side of the Pt oxide layer away from the substrate to obtain a base sample; Annealing the basic sample at 200° C. for 1 h to obtain an annealed sample; Depositing the Co layer with a thickness of 0.8 nm to 0.9 nm on the side of the Pt layer away from the substrate in the annealed sample; forming the IrMn layer with a thickness of 1 nm on a side of the Co layer away from the substrate; sputtering a Ta layer with a thickness of 3 nm on a side of the IrMn layer away from the substrate as the protective layer to obtain an initial sample; Processing the initial sample into the Hall bar cross structure with a Hall bar width of 75 μm by using a photolithography process and an etching process; Four electrodes are prepared by electron beam deposition, and the four electrodes are respectively connected to the four ends of the Hall bar cross structure.

10. The method according to claim 8 or 9, characterized in that The anisotropic magnetoresistive strip comprises a buffer layer, a NiFe layer and a protective layer sequentially arranged in a direction away from the substrate; Forming the X-axis direction sensor or the Y-axis direction sensor includes: sputtering a Ta layer on one side of the substrate as a buffer layer in the anisotropic magnetoresistive strip; Sputtering a NiFe layer with a thickness of 45 nm on a side of the buffer layer in the anisotropic magnetoresistive strip away from the substrate; sputtering a Ta layer on a side of the NiFe layer away from the substrate as a protective layer in the anisotropic magnetoresistive strip to obtain an original sample; Processing the original sample into the anisotropic magnetoresistive strip with a width of 80 μm by using a photolithography process and an etching process; A Babe electrode is prepared, and the Babe electrode is connected to the corresponding anisotropic magnetoresistive strip.

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