TMR full-bridge magnetic sensor and biaxial TMR full-bridge magnetic sensor

Abstract

The invention provides a TMR full-bridge magnetic sensor and a double-shaft TMR full-bridge magnetic sensor. The TMR full-bridge magnetic sensor comprises a substrate and four MTJ units located on the surface of the substrate, one MTJ unit comprises a bottom electrode, an MTJ and a top electrode which are sequentially stacked in the preset direction, the four MTJ units are connected in a bridge mode to form a Wheatstone full-bridge structure, the four MTJ units form four bridge arms of the Wheatstone full-bridge structure respectively, and the bottom electrode, the MTJ and the top electrode are sequentially stacked in the preset direction. One end of any MTJ unit is electrically connected with the adjacent MTJ unit on one side through a top electrode, the other end of any MTJ unit is electrically connected with the adjacent MTJ unit on the other side through a bottom electrode, the bottom electrode is used for injecting pulse current and setting the magnetization direction of the reference layer, and the flow directions of the pulse current on the adjacent bridge arms are opposite; the preset direction is the thickness direction of the substrate. According to the TMR full-bridge magnetic sensor, the problems of high difficulty and high cost of constructing a TMR full-bridge magnetic sensor in the prior art are solved.

Description

Technical Field

[0001] The present application relates to the field of magnetic field detection technology, and in particular to a TMR full-bridge magnetic sensor and a dual-axis TMR full-bridge magnetic sensor. Background Art

[0002] As an emerging sensor, TMR (Tunnel Magneto Resistance) sensor is widely used in consumer electronics, industrial electronics and other fields. The sensor uses the tunnel magnetoresistance effect of magnetic multilayer film to detect external magnetic field, which is mainly manifested in that the resistance of the magnetic multilayer film changes with the size and angle of the magnetic field. Compared with the widely used Hall and AMR (Anisotropic Magneto Resistance) sensors, it has the advantages of high sensitivity, small size, low power consumption and high resolution.

[0003] Since the resistance of the material changes with temperature, in order to suppress temperature drift and enhance the working stability of the device, a Wheatstone full-bridge structure is required. At this time, the magnetoresistance units on adjacent bridge arms have opposite output trends for the same magnetic field, which requires that the magnetization directions of the pinned layers of the magnetoresistance units on adjacent bridge arms are opposite. At present, the methods for constructing a full bridge include mechanical splicing, multiple deposition and coating, laser local annealing, magnetic flux concentrators, etc. These methods have the disadvantages of limited accuracy, complex process, unsuitability for large-scale process integration, and high cost.

[0004] Therefore, a convenient and low-cost solution for constructing a TMR Wheatstone full-bridge sensor is needed. Summary of the invention

[0005] The main purpose of the present application is to provide a TMR full-bridge magnetic sensor and a dual-axis TMR full-bridge magnetic sensor to solve the problem of high difficulty and high cost in constructing a TMR full-bridge magnetic sensor in the prior art.

[0006] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a TMR full-bridge magnetic sensor is provided, which includes a substrate and four MTJ (Magnetic Tunnel Junction) units located on the surface of the substrate, one of the MTJ units includes a bottom electrode, an MTJ and a top electrode stacked in sequence along a predetermined direction, the four MTJ units are bridge-connected to form a Wheatstone full-bridge structure, and the four MTJ units respectively constitute four bridge arms of the Wheatstone full-bridge structure, one end of any one of the MTJ units is electrically connected to the MTJ unit adjacent to one side through the top electrode, and the other end of any one of the MTJ units is electrically connected to the MTJ unit adjacent to the other side through the bottom electrode, the bottom electrode is used to inject a pulse current and set the magnetization direction of the reference layer, and the pulse currents on adjacent bridge arms flow in opposite directions, and the predetermined direction is the direction of the thickness of the substrate.

[0007] Further, the bottom electrode serves as an input electrode and the top electrode serves as an output electrode, or the bottom electrode serves as the output electrode and the top electrode serves as the input electrode.

[0008] Furthermore, each of the MTJ units includes at least two MTJs, at least two of the MTJs are spaced apart and arranged between the bottom electrode and the top electrode, and any two of the MTJs are connected in parallel.

[0009] Furthermore, one of the MTJs at least includes a reference layer, a barrier layer, and a free layer stacked in sequence along the predetermined direction.

[0010] Furthermore, the bottom electrode at least includes a seed layer and a spin-orbit layer stacked in sequence along the predetermined direction.

[0011] Furthermore, the reference layer in the MTJ has in-plane anisotropy, and the material of the spin-track layer includes one of IrMn, PtMn, PdMn, NiO and α-Fe2O3.

[0012] Further, the reference layer in the MTJ has in-plane anisotropy, and the shape of the cross section of the MTJ along the perpendicular direction is one of an ellipse, a rectangle and a hexagon.

[0013] Furthermore, the reference layer in the MTJ has in-plane anisotropy, and the long axis direction of any one of the MTJs is the same as the direction of the pulse current of the corresponding MTJ.

[0014] Furthermore, the reference layer in the MTJ has perpendicular anisotropy, and the material of the spin-track layer includes Ta, Ir, Mo, Hf, Bi2Se3, Sb2Te3, (Bix Sb 1-x )2Te3 and one of the two-dimensional electron gases.

[0015] Further, the reference layer in the MTJ has perpendicular anisotropy, and the shape of the cross section of the MTJ along the perpendicular direction is one of an ellipse, a rectangle, a hexagon and a circle.

[0016] Further, the polarities of the pulse currents respectively corresponding to the two MTJ units connected through the top electrode are the same, and the polarities of the pulse currents respectively corresponding to the two MTJ units connected through the bottom electrode are opposite.

[0017] According to another aspect of the present application, a dual-axis TMR full-bridge magnetic sensor is provided, comprising two TMR full-bridge magnetic sensors of any one type, wherein the two TMR full-bridge magnetic sensors are placed orthogonally.

[0018] Applying the technical solution of the present application, the TMR full-bridge magnetic sensor includes a substrate and four MTJ units located on the surface of the substrate, one of the MTJ units includes a bottom electrode, an MTJ and a top electrode stacked in sequence along a predetermined direction, the four MTJ units are bridge-connected to form a Wheatstone full-bridge structure, the four MTJ units respectively constitute four bridge arms of the Wheatstone full-bridge structure, one end of any one of the MTJ units is electrically connected to the MTJ unit adjacent to one side through the top electrode, the other end of any one of the MTJ units is electrically connected to the MTJ unit adjacent to the other side through the bottom electrode, the bottom electrode is used to inject a pulse current and set the magnetization direction of the reference layer, and the pulse currents on adjacent bridge arms flow in opposite directions, and the predetermined direction is the direction of the thickness of the substrate. The bottom electrode of the TMR full-bridge magnetic sensor is used to inject a pulse current and set the magnetization direction of the reference layer, and the pulse currents on adjacent bridge arms flow in opposite directions. When current passes through the bottom electrode, a vertical spin current is generated inside the bottom electrode. The spin current produces a spin-orbit torque effect on the MTJ of the MTJ unit, thereby achieving opposite magnetization directions of the reference layers of the MTJ units on adjacent bridge arms. Therefore, the TMR full-bridge magnetic sensor does not require annealing during sample preparation, simplifies the experimental process, reduces the difficulty of the preparation process, saves production costs, and solves the problem of difficulty and high cost in constructing a TMR full-bridge magnetic sensor in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings constituting part of the present application are used to provide a further understanding of the present application. The exemplary embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0020] Figure 1A schematic diagram of setting a pulse current for a TMR full-bridge magnetic sensor according to an embodiment of the present application is shown;

[0021] Figure 2 A schematic diagram showing the operation of a TMR full-bridge magnetic sensor according to an embodiment of the present application is shown;

[0022] Figure 3 A schematic diagram of the structure of an MTJ unit after forming a free layer according to an embodiment of the present application is shown;

[0023] Figure 4 A schematic diagram of the structure of an MTJ unit after forming an MTJ according to an embodiment of the present application is shown;

[0024] Figure 5 A schematic diagram of the structure of an MTJ unit after forming a first dielectric layer according to an embodiment of the present application is shown;

[0025] Figure 6 A schematic diagram of the structure of an MTJ unit after forming a bottom electrode according to an embodiment of the present application is shown;

[0026] Figure 7 A schematic diagram of the structure of an MTJ unit after forming a second dielectric layer according to an embodiment of the present application is shown;

[0027] Figure 8 A schematic diagram of the structure of an MTJ unit after etching the second dielectric layer according to an embodiment of the present application is shown;

[0028] Fig. 9 A schematic diagram of the structure of an MTJ unit after forming a top electrode according to an embodiment of the present application is shown;

[0029] Fig.10 A schematic structural diagram of an MTJ unit after forming a top electrode according to another embodiment of the present application is shown;

[0030] Fig.11 A schematic structural diagram of a dual-axis TMR full-bridge magnetic sensor according to an embodiment of the present application is shown.

[0031] The above drawings include the following reference numerals:

[0032] 10. Substrate; 20. MTJ unit; 201. Bottom electrode; 202. MTJ; 203. Top electrode; 204. First dielectric layer; 205. Second dielectric layer; 211. Seed layer; 212. Metal layer; 213. Spin-orbit layer; 221. Reference layer; 222. Barrier layer; 223. Free layer; 224. Artificially synthesized antiferromagnetic structure; 225. Guide layer; 226. Coupling layer; 227. Antiferromagnetic layer. DETAILED DESCRIPTION

[0033] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0034] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0035] It should be understood that when an element (such as a layer, film, region, or substrate) is described as being "on" another element, the element may be directly on the other element, or there may be intermediate elements. Moreover, in the specification and claims, when an element is described as being "connected" to another element, the element may be "directly connected" to the other element, or "connected" to the other element through a third element.

[0036] As introduced in the background technology, it is difficult and costly to construct a TMR full-bridge magnetic sensor in the prior art. To solve the above problems, the embodiments of the present application provide a TMR full-bridge magnetic sensor and a dual-axis TMR full-bridge magnetic sensor.

[0037] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0038] In a typical embodiment of the present application, a TMR full-bridge magnetic sensor is provided, such as Figure 1 As shown, the TMR full-bridge magnetic sensor includes a substrate 10 and four MTJ units 20 located on the surface of the substrate 10, one of the MTJ units 20 includes a bottom electrode 201, an MTJ 202 and a top electrode 203 stacked in sequence along a predetermined direction, the four MTJ units 20 are bridge-connected to form a Wheatstone full-bridge structure, the four MTJ units 20 respectively constitute four bridge arms of the Wheatstone full-bridge structure, one end of any one of the MTJ units 20 is electrically connected to the MTJ unit 20 adjacent to one side through the top electrode 203, the other end of any one of the MTJ units 20 is electrically connected to the MTJ unit 20 adjacent to the other side through the bottom electrode 201, the bottom electrode 201 is used to inject a pulse current and set the magnetization direction of the reference layer, and the pulse currents on the adjacent bridge arms flow in opposite directions, and the predetermined direction is the direction of the thickness of the substrate 10.

[0039] The above-mentioned TMR full-bridge magnetic sensor includes a substrate and four MTJ units located on the surface of the above-mentioned substrate, one of the above-mentioned MTJ units includes a bottom electrode, an MTJ and a top electrode stacked in sequence along a predetermined direction, the four above-mentioned MTJ units are bridge-connected to form a Wheatstone full-bridge structure, and the four above-mentioned MTJ units respectively constitute four bridge arms of the above-mentioned Wheatstone full-bridge structure, one end of any one of the above-mentioned MTJ units is electrically connected to the above-mentioned MTJ unit adjacent to one side through the above-mentioned top electrode, and the other end of any one of the above-mentioned MTJ units is electrically connected to the above-mentioned MTJ unit adjacent to the other side through the above-mentioned bottom electrode, and the above-mentioned bottom electrode is used to inject pulse current and set the magnetization direction of the reference layer, and the flow direction of the above-mentioned pulse current on the adjacent above-mentioned bridge arms is opposite, and the above-mentioned predetermined direction is the direction of the thickness of the above-mentioned substrate. The bottom electrode of the TMR full-bridge magnetic sensor is used to inject a pulse current and set the magnetization direction of the reference layer, and the pulse currents on adjacent bridge arms flow in opposite directions. When current passes through the bottom electrode, a vertical spin current is generated inside the bottom electrode. The spin current produces a spin-orbit torque effect on the MTJ of the MTJ unit, thereby achieving opposite magnetization directions of the reference layers of the MTJ units on adjacent bridge arms. Therefore, the TMR full-bridge magnetic sensor does not require annealing during sample preparation, simplifies the experimental process, reduces the difficulty of the preparation process, saves production costs, and solves the problem of difficulty and high cost in constructing a TMR full-bridge magnetic sensor in the prior art.

[0040] In practical applications, magnetoresistive sensors have attracted great attention due to their high sensitivity to magnetic fields and excellent thermal stability, and their linear rather than hysteretic magnetoresistive response to external magnetic fields. Among them, TMR magnetoresistive sensors are a type of magnetoresistive sensors. Compared with AMR (Anisotropy Magneto Resistance) sensors and GMR (Giant Magneto Resistance) sensors, they have the advantages of greater resistance change rate, better temperature characteristics and linearity, and have been widely used in the industrial field in recent years. Magnetoresistive sensors with a full-bridge structure can effectively improve the sensitivity and temperature stability of the device. Since the magnetoresistive change of the TMR sensor itself comes from the relative orientation of the magnetization of the reference layer and the free layer in the MTJ, the TMR sensor with a full-bridge structure needs to achieve the opposite magnetization direction of the reference layer of the MTJ units on adjacent bridge arms. Usually in the same device, the MTJ units prepared at one time have the same magnetization direction of the reference layer of the MTJ units on the bridge arms due to the same preparation process, making it difficult to form a full-bridge structure at one time.

[0041] Specifically, when testing the MTJ, it is necessary to read the current flowing from the top electrode to the bottom electrode (or from the bottom electrode to the top electrode), and when setting the magnetization direction of the MTJ reference layer, a pulse current needs to flow through the bottom heavy metal current channel. Figure 1 As shown, one end of any of the above MTJ units is electrically connected to the MTJ unit adjacent to one side through the above top electrode, and the other end of any of the above MTJ units is electrically connected to the MTJ unit adjacent to the other side through the above bottom electrode. Pulse current I is applied to the left and right loops respectively, and the directions of the pulse currents in the left and right loops are fixed to be opposite, so that the magnetization directions of multiple MTJ pinned layers on adjacent bridge arms can be opposite. The above method of setting the magnetization direction of the reference layer is simple, low-cost, and the reference layer magnetization direction initialization operation is simple. The magnetization directions of two bridge arms can be set at one time, which is highly efficient.

[0042] After the magnetization direction of the MTJ reference layer is set, the pulse current is removed, such as Figure 2 As shown, when the TMR full-bridge magnetic sensor is working, a test voltage is applied to the Vcc terminal, and the output voltage is measured at the Voutput terminal, and the positions of Vcc and Voutput can be interchanged. In one embodiment of the present application, the bottom electrode is used as the input electrode and the top electrode is used as the output electrode, or the bottom electrode is used as the output electrode and the top electrode is used as the input electrode.

[0043] In order to adjust the size of the resistance and reduce the noise level, in another embodiment of the present application, each of the above-mentioned MTJ units includes at least two MTJs, at least two of the above-mentioned MTJs are spaced apart between the above-mentioned bottom electrode and the above-mentioned top electrode, and any two of the above-mentioned MTJs are connected in parallel.

[0044] Specifically, when MTJ is used as a sensor, according to the sensor noise level formula Among them, A is the total sensing area of ​​the device. It can be seen that increasing A can effectively reduce the noise level. The current common practice is to use multiple tunnel junctions in series and parallel to form an array structure to increase the total sensing area. In addition, in addition to reducing the noise level, the MTJ itself is very easy to be broken down and short-circuited, so forming an array structure can also greatly reduce the risk of short circuits, such as Figure 1 and Figure 2 As shown, the MTJs in an MTJ unit can be arranged in an array, and the magnetization direction of the reference layer on the entire Wheatstone bridge structure can be set at one time.

[0045] In another embodiment of the present application, the MTJ at least comprises a reference layer, a barrier layer and a free layer stacked in sequence along the predetermined direction. MTJ is a magnetic tunnel junction, which is a sandwich structure non-uniform magnetic system of ferromagnetic metal / insulator / ferromagnetic metal. The ferromagnetic metal can be a reference layer or a free layer, and the insulator is a barrier layer. The spin polarization tunneling process of the metal oxide (usually aluminum oxide) barrier between two ferromagnetic metal films (such as chromium, cobalt, nickel or iron nickel) can also produce a giant magnetoresistance effect.

[0046] In practical applications, MTJ is formed by at least two ferromagnetic layers (reference layer and free layer), each of which can maintain a magnetic field or polarization and is separated by a thin non-magnetic insulating layer (tunneling barrier). Due to the tunneling effect under the bias voltage applied to the ferromagnetic layer, electrons from the two ferromagnetic layers can penetrate the tunneling barrier. The magnetic polarization of the free layer can be reversed so that the polarity of the reference layer and the free layer is generally aligned (parallel) or opposite (anti-parallel). The resistance of the electrical path through the MTJ will vary depending on the alignment of the polarization of the pinned layer and the free layer.

[0047] In another embodiment of the present application, the bottom electrode at least includes a seed layer and a spin-orbit layer stacked in sequence along the predetermined direction. The seed layer can provide a suitable crystal orientation and flatness for the multiple layers grown thereon, and there can also be a metal layer between the seed layer and the spin-orbit layer. The main function of the metal layer is to provide auxiliary function for the flipping of the spin-orbit torque (SOT). SOT refers to the generation of spin-orbit torque based on spin-orbit coupling (SOC), using the spin current induced by the charge flow, so as to achieve the purpose of regulating the magnetic storage unit.

[0048] In order to enable the TMR full-bridge magnetic sensor to detect in-plane magnetic fields, in another embodiment of the present application, the reference layer in the MTJ has in-plane anisotropy, and the material of the spin-track layer includes one of IrMn, PtMn, PdMn, NiO and α-Fe2O3.

[0049] In a specific embodiment, an IrMn-based in-plane thin film may be used to detect the in-plane magnetic field. The preparation method of the MTJ unit in this embodiment is as follows:

[0050] S101, preparing a thin film structure, depositing on a substrate in sequence: Figure 3The thin film structure shown. A substrate 10 is provided, and a seed layer 211 is formed on the surface of the substrate 10. The material of the seed layer 211 can be selected from at least one of Ta, Ru, NiFe, NiFeCr and CoFe. A metal layer 212 is formed on the surface of the seed layer 211 away from the substrate 10. The material of the metal layer 212 can be selected from a conductor material such as Pt, Ir, Cu and Au. A spin-track layer 213 is formed on the surface of the metal layer 212 away from the seed layer 211. In addition to IrMn, the material of the spin-track layer 213 can also be replaced by an antiferromagnetic material such as PtMn, PdMn, NiO and α-Fe2O3. An artificial antiferromagnetic structure 224 is formed on the surface of the spin-track layer 213 away from the metal layer 212. The artificial antiferromagnetic structure 224 includes a guide layer 225, a coupling layer 226 and a reference layer 221 stacked in sequence, and its main function is to reduce stray fields. The material of the guide layer 225 can be CoFe, the material of the coupling layer 226 can be Ru, and the material of the reference layer 221 can be CoFeB. Ru is used to cause the coupling of CoFe and CoFeB so that their magnetization directions are opposite. CoFe is used to guide the magnetic moment direction of CoFeB and ensure its stability. A barrier layer 222 and a free layer 223 are stacked in sequence on the surface of the reference layer 221 away from the coupling layer 226. The material of the barrier layer 222 can be MgO. The material of the free layer 223 can be one of CoFeB, NiFe and CoFeSiB or a combination thereof. The so-called artificial antiferromagnetic structure usually refers to the exchange coupling between two ferromagnetic layers through a non-magnetic interlayer. This coupling makes the magnetic moments of the two ferromagnetic layers appear antiparallel and can maintain this antiparallel state within a certain range of external magnetic field.

[0051] S102, such as Figure 3 and Figure 4 As shown, part of the free layer 223, part of the barrier layer 222, part of the reference layer 221 in the artificial synthetic antiferromagnetic structure 224, and part of the coupling layer 226 are removed by photolithography and etching, so that a portion of the surface of the guide layer 225 in the artificial synthetic antiferromagnetic structure away from the spin-track layer 213 is exposed, and the remaining free layer 223, the remaining barrier layer 222, the remaining reference layer 221, and the remaining coupling layer 226 form a plurality of spaced MTJs 202, as shown in FIG. Figure 5 As shown, a first dielectric layer 204 is deposited on the guide layer 225 and the exposed surface of the MTJ 202 to prevent the MTJ 202 from being oxidized. In practical applications, the etching stops above the spin-track layer 213 , that is, the MTJ 202 may also include the guide layer 225 after etching.

[0052] S103, such as Figure 5 and Figure 6 As shown, the shape of the bottom electrode 201 is defined by photolithography and etching, and then the first dielectric layer 204 is etched by stripping, and part of the guide layer 225, part of the spin-track layer 213, part of the metal layer 212 and part of the seed layer 211 are removed to form a plurality of bottom electrodes 201;

[0053] S104, such as Figure 7 As shown, a second dielectric layer 205 is deposited to cover the multiple MTJs 202 and the multiple bottom electrodes 201;

[0054] S105, such as Figure 8 As shown, photolithography and etching are performed on the second dielectric layer 205 to form a groove, so that the surface of the MTJ 202 away from the bottom electrode 201 is exposed, as shown in FIG. Fig. 9 As shown, a top electrode 203 is deposited on the surface of the MTJ 202 and the remaining second dielectric layer 205;

[0055] S106, after the device is prepared, a current density of 10 6 ~10 7 A / cm 2 The pulse current with a pulse width of ns to ms is used to complete the preparation of the TMR Wheatstone full-bridge structure.

[0056] The preparation of the above-mentioned MTJ unit is highly integrated with the existing process steps, without adding additional process steps. It is made of the same film stack, has a small resistance difference between the bridge arms, and has a stable full-bridge output.

[0057] In another embodiment of the present application, the reference layer in the MTJ has in-plane anisotropy, and the shape of the cross section of the MTJ along the predetermined direction perpendicular to the predetermined direction is one of an ellipse, a rectangle and a hexagon. The ellipse, rectangle and hexagon can make the free layer of each MTJ easy to form a stable single domain structure.

[0058] In practical applications, the single-domain structure of MTJ means that there is only one magnetic domain in the magnetic tunnel junction. When an external voltage is applied, the resistance value can be changed by adjusting the spin polarization state in the tunnel layer. And "only one magnetic domain" means that in the tunnel layer, there is only one spin polarization region (also called a magnetic domain) with a specific direction, and this specific direction can be used as an information bit. Therefore, there is only one determined spin state in the magnetic tunnel junction, which can realize efficient and reliable read and write operations, and can increase the storage density to a very high level.

[0059] In another embodiment of the present application, the reference layer in the MTJ has in-plane anisotropy, and the long axis direction of any one of the MTJs is the same as the direction of the pulse current of the corresponding MTJ. The long axis direction of the MTJ refers to the direction in which the distance between the two ferromagnetic electrodes in the magnetic tunnel structure is longer, the magnetic moment of the free layer will be arranged along the long axis direction, the magnetization direction of the reference layer will be arranged along the short axis direction after the pulse current is passed, and the magnetic field to be detected by the sensor is perpendicular to the long axis direction, that is, along the short axis direction.

[0060] In order to enable the TMR full-bridge magnetic sensor to detect a perpendicular magnetic field, in another embodiment of the present application, the reference layer in the MTJ has a perpendicular anisotropy, and the material of the spin-track layer includes Ta, Ir, Mo, Hf, Bi2Se3, Sb2Te3, (Bi x Sb 1-x )2Te3 and one of the two-dimensional electron gases.

[0061] In practical applications, perpendicular anisotropy can have higher thermal stability than in-plane anisotropy, which means that materials with perpendicular anisotropy can be prepared into smaller storage units, thus becoming a key factor in the preparation of high-density storage materials. In terms of TMR, magnetic tunnels with perpendicular magnetic anisotropic ferromagnetic electrodes (hereinafter referred to as vertical tunnel junctions) are believed to be able to realize the next generation of high-density non-volatile memory - magnetic random access memory (MRAM). This is mainly because compared with in-plane magnetic tunnel junctions, vertical tunnel junctions can overcome the edge effect at small scales, have a higher magnetoresistance and a higher signal-to-noise ratio; have greater anisotropy, stronger resistance to thermal disturbances, and a smaller superparamagnetic limit size, so the density of the device can be made higher and more reliable; relatively speaking, the critical reversal current reduces a quantity related to static magnetoenergy, so it can be smaller. In a vertical tunnel junction, the reference layer should have perpendicular anisotropy, which means that the reference layer is mostly prepared using materials with perpendicular anisotropy.

[0062] In another specific embodiment, a CoPt-based film with perpendicular anisotropy can be used to detect the perpendicular magnetic field. The preparation method of the MTJ unit in this embodiment is similar to the preparation method of the MTJ unit of the in-plane film, and finally forms Fig.10 The structure shown in the figure includes a substrate 10, a bottom electrode 201, an MTJ 202, a second dielectric layer 205 and a top electrode 203. A plurality of bottom electrodes 201 are arranged on the surface of the substrate 10 at intervals. Each bottom electrode 201 includes a seed layer 211 and a spin-track layer 213 stacked in sequence. The material of the spin-track layer 213 can be heavy metals such as Pt, Ta, Ir, Mo and Hf, or Bi2Se3, Sb2Te3 or (Bi x Sb 1-x)2Te3 crystal film, or any structure that can generate spin current such as two-dimensional electron gas; a plurality of MTJs 202 are arranged on the surface of each bottom electrode 201 away from the substrate 10, and one MTJ 202 includes a guide layer 225, a coupling layer 226, an antiferromagnetic layer 227, a reference layer 221, a barrier layer 222 and a free layer 223 stacked in sequence, and the material of the guide layer 225 can be [Co / Pt] m , the material of the coupling layer 226 can be Ru, and the material of the antiferromagnetic layer 227 can be [Co / Pt] n The material of the reference layer 221 can be a ferromagnetic material such as CoFeB, Co, etc., and the free layer 223 can be a single free layer structure such as a CoFeB single layer, or a double free layer structure such as CoFeB / Ta / CoFeB. The MTJ etching should stop above the spin-track layer 213 to ensure that the current can flow through the spin-track layer 213. The second dielectric layer 205 covers the sidewalls of the MTJ202 and the bottom electrode 201; the top electrode 203 is located on the side of the MTJ202 away from the bottom electrode 201, and the top electrode 203 is in contact with the surface of the free layer 223 of the MTJ202 away from the barrier layer 222 and the second dielectric layer 205. When setting the magnetization direction of the reference layer, while applying current pulses to the left and right paths, an in-plane field along the current direction needs to be applied to achieve the reversal of the magnetic moment direction, and the direction of the magnetic field should be consistent for the left and right loops.

[0063] Since in a perpendicular anisotropic structure, the shape of the cross section of the MTJ along the predetermined direction perpendicular to the above-mentioned predetermined direction may be a structure without shape anisotropy, in another embodiment of the present application, the reference layer in the above-mentioned MTJ has perpendicular anisotropy, and the shape of the cross section of the above-mentioned MTJ along the predetermined direction perpendicular to the above-mentioned predetermined direction is one of an ellipse, a rectangle, a hexagon and a circle.

[0064] In order to achieve the opposite magnetization directions of multiple MTJ reference layers on adjacent bridge arms, Figure 1 As shown, in another embodiment of the present application, the polarities of the pulse currents respectively corresponding to the two MTJ units 20 connected through the top electrode 203 are the same, and the polarities of the pulse currents respectively corresponding to the two MTJ units 20 connected through the bottom electrode 201 are opposite.

[0065] According to another aspect of the present application, a dual-axis TMR full-bridge magnetic sensor is provided, comprising two of any one of the above-mentioned TMR full-bridge magnetic sensors, wherein the two TMR full-bridge magnetic sensors are placed orthogonally.

[0066] The above-mentioned dual-axis TMR full-bridge magnetic sensor includes two of any one of the above-mentioned TMR full-bridge magnetic sensors. The two above-mentioned TMR full-bridge magnetic sensors are placed orthogonally. After pulse currents are respectively passed through them, the in-plane two-axis magnetic field sensors are integrated on the same chip.

[0067] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the TMR full-bridge magnetic sensor of the present application will be described in detail below in conjunction with specific embodiments.

[0068] Example 1

[0069] This embodiment provides a TMR full-bridge magnetic sensor, such as Figure 1 As shown, the TMR full-bridge magnetic sensor includes a substrate 10 and four MTJ units 20 located on the surface of the substrate 10, one of the MTJ units 20 includes a bottom electrode 201, an MTJ 202 and a top electrode 203 stacked in sequence along a predetermined direction, the four MTJ units 20 are bridge-connected to form a Wheatstone full-bridge structure, the four MTJ units 20 respectively constitute four bridge arms of the Wheatstone full-bridge structure, one end of any one of the MTJ units 20 is electrically connected to the MTJ unit 20 adjacent to one side through the top electrode 203, the other end of any one of the MTJ units 20 is electrically connected to the MTJ unit 20 adjacent to the other side through the bottom electrode 201, the bottom electrode 201 is used to inject a pulse current and set the magnetization direction of the reference layer, and the pulse currents on the adjacent bridge arms flow in opposite directions, and the predetermined direction is the direction of the thickness of the substrate 10.

[0070] This implementation example Fig. 9 As shown, a plurality of bottom electrodes 201 are arranged at intervals on the surface of the substrate 10, and each of the bottom electrodes includes a seed layer 211, a metal layer 212, a spin-track layer 213 and a guide layer 225 stacked in sequence along the predetermined direction; a plurality of MTJs 202 are arranged at intervals on the surface of each bottom electrode 201 away from the substrate 10, and the MTJ 202 includes a coupling layer 226, a reference layer 221, a barrier layer 222 and a free layer 223 stacked in sequence along the predetermined direction; the second dielectric layer 205 covers the side wall of the MTJ 202 and the bottom electrode 201; the top electrode 203 is located on the side of the MTJ 202 away from the bottom electrode 201, and the top electrode 203 is in contact with the surface of the free layer 223 of the MTJ 202 away from the barrier layer 222 and in contact with the second dielectric layer 205.

[0071] Example 2

[0072] The difference between Example 2 and Example 1 is that the bottom electrode and the MTJ film layer are different. Fig.10As shown, the bottom electrode 201 includes a seed layer 211 and a spin-track layer 213 stacked in sequence along the above predetermined direction, and the MTJ includes a guide layer 225, a coupling layer 226, an antiferromagnetic layer 227, a reference layer 221, a barrier layer 222 and a free layer 223 stacked in sequence along the above predetermined direction.

[0073] Example 3

[0074] like Fig.11 As shown, it includes two TMR full-bridge magnetic sensors described above in any one of the first embodiments. The two TMR full-bridge magnetic sensors are placed orthogonally. After pulse currents are respectively passed through them, the in-plane two-axis magnetic field sensors are integrated on the same chip.

[0075] From the above description, it can be seen that the above embodiments of the present application achieve the following technical effects:

[0076] 1) The TMR full-bridge magnetic sensor of the present application comprises a substrate and four MTJ units located on the surface of the substrate, wherein one of the MTJ units comprises a bottom electrode, an MTJ and a top electrode stacked in sequence along a predetermined direction, the four MTJ units are bridge-connected to form a Wheatstone full-bridge structure, the four MTJ units respectively constitute four bridge arms of the Wheatstone full-bridge structure, one end of any one of the MTJ units is electrically connected to the MTJ unit adjacent to one side through the top electrode, the other end of any one of the MTJ units is electrically connected to the MTJ unit adjacent to the other side through the bottom electrode, the bottom electrode is used to inject a pulse current and set the magnetization direction of the reference layer, and the pulse currents on adjacent bridge arms flow in opposite directions, and the predetermined direction is the direction of the thickness of the substrate. The bottom electrode of the TMR full-bridge magnetic sensor is used to inject a pulse current and set the magnetization direction of the reference layer, and the pulse currents on adjacent bridge arms flow in opposite directions. When current passes through the bottom electrode, a vertical spin current is generated inside the bottom electrode. The spin current produces a spin-orbit torque effect on the MTJ of the MTJ unit, thereby achieving opposite magnetization directions of the reference layers of the MTJ units on adjacent bridge arms. Therefore, the TMR full-bridge magnetic sensor does not require annealing during sample preparation, simplifies the experimental process, reduces the difficulty of the preparation process, saves production costs, and solves the problem of difficulty and high cost in constructing a TMR full-bridge magnetic sensor in the prior art.

[0077] 2) The above-mentioned dual-axis TMR full-bridge magnetic sensor of the present application includes two of any one of the above-mentioned TMR full-bridge magnetic sensors. The two above-mentioned TMR full-bridge magnetic sensors are placed orthogonally, and after pulse currents are respectively passed through them, the in-plane two-axis magnetic field sensors are integrated on the same chip.

[0078] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A TMR full-bridge magnetic sensor, characterized in that: It includes a substrate and four MTJ units located on the surface of the substrate, one of the MTJ units includes a bottom electrode, an MTJ and a top electrode stacked in sequence along a predetermined direction, the four MTJ units are bridge-connected to form a Wheatstone full-bridge structure, the four MTJ units respectively constitute four bridge arms of the Wheatstone full-bridge structure, one end of any one of the MTJ units is electrically connected to the MTJ unit adjacent to one side through the top electrode, the other end of any one of the MTJ units is electrically connected to the MTJ unit adjacent to the other side through the bottom electrode, the bottom electrode is used to inject a pulse current and set the magnetization direction of the reference layer, and the pulse currents on adjacent bridge arms flow in opposite directions, and the predetermined direction is the direction of the thickness of the substrate.

2. The TMR full-bridge magnetic sensor according to claim 1, characterized in that: The bottom electrode serves as an input electrode and the top electrode serves as an output electrode, or the bottom electrode serves as the output electrode and the top electrode serves as the input electrode.

3. The TMR full-bridge magnetic sensor according to claim 1, characterized in that: Each of the MTJ units includes at least two MTJs, at least two of the MTJs are spaced apart and arranged between the bottom electrode and the top electrode, and any two of the MTJs are connected in parallel.

4. The TMR full-bridge magnetic sensor according to claim 1, characterized in that: One of the MTJs at least includes a reference layer, a barrier layer, and a free layer sequentially stacked along the predetermined direction.

5. The TMR full-bridge magnetic sensor according to claim 1, characterized in that: The bottom electrode at least includes a seed layer and a spin-orbit layer sequentially stacked along the predetermined direction.

6. The TMR full-bridge magnetic sensor according to claim 5, characterized in that: The reference layer in the MTJ has in-plane anisotropy, and the material of the spin-track layer includes one of IrMn, PtMn, PdMn, NiO and α-Fe2O3.

7. The TMR full-bridge magnetic sensor according to claim 5, characterized in that: The reference layer in the MTJ has in-plane anisotropy, and a cross-section of the MTJ along a direction perpendicular to the predetermined direction has a shape selected from the group consisting of an ellipse, a rectangle, and a hexagon.

8. The TMR full-bridge magnetic sensor according to claim 5, characterized in that: The reference layer in the MTJ has in-plane anisotropy, and the long axis direction of any one of the MTJs is the same as the direction of the pulse current of the corresponding MTJ.

9. The TMR full-bridge magnetic sensor according to claim 5, characterized in that: The reference layer in the MTJ has perpendicular anisotropy, and the material of the spin-track layer includes Ta, Ir, Mo, Hf, Bi2Se3, Sb2Te3, (Bi x Sb 1-x )2Te3 and one of the two-dimensional electron gases.

10. The TMR full-bridge magnetic sensor according to claim 5, characterized in that: The reference layer in the MTJ has perpendicular anisotropy, and a cross-section of the MTJ along a direction perpendicular to the predetermined direction has a shape selected from the group consisting of an ellipse, a rectangle, a hexagon, and a circle.

11. The TMR full-bridge magnetic sensor according to any one of claims 1 to 10, characterized in that: The polarities of the pulse currents respectively corresponding to the two MTJ units connected through the top electrode are the same, and the polarities of the pulse currents respectively corresponding to the two MTJ units connected through the bottom electrode are opposite.

12. A dual-axis TMR full-bridge magnetic sensor, characterized in that: The method comprises two TMR full-bridge magnetic sensors according to any one of claims 1 to 11, wherein the two TMR full-bridge magnetic sensors are placed orthogonally.

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