Magnetic sensor and preparation method thereof

Abstract

The invention provides a magnetic sensor and a preparation method thereof, and relates to the technical field of semiconductor devices and processes, and the method comprises the steps: carrying out the etching of a first substrate, and forming a first projection; forming a second substrate on the etched first substrate, wherein the second substrate is provided with a first recess corresponding to the first bulge; a first magnetic resistor, a second magnetic resistor, a third magnetic resistor and a fourth magnetic resistor which are in full-bridge connection are formed on the second substrate, the first magnetic resistor and the third magnetic resistor are located on one side of the first recess, and the second magnetic resistor and the fourth magnetic resistor are located on the other side of the first recess; stripping the first substrate to obtain a magnetic sensor body; the magnetic sensor body is folded along the first recess. According to the invention, by folding the magnetic sensor body along the first recess, the two adjacent magnetoresistance elements are folded, so that the magnetoresistance units on the two adjacent bridge arms of the Wheatstone full-bridge structure have opposite magnetic pinning directions, the stability of the performance of the magnetic sensor is improved, and the process is relatively simple.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor devices and process technology, and in particular to a magnetic sensor and a method for preparing the magnetic sensor. Background Art

[0002] In recent years, the Internet of Things and intelligent technology have flourished. Magnetic sensors have played an important role in the development of the Internet of Things and intelligent technology. Therefore, it is very important to ensure the performance of magnetic sensors. The output of magnetic sensors changes due to temperature changes, resulting in instability of magnetic sensors. In order to improve the temperature stability of magnetic sensors, it is required that the magnetoresistance units on the two adjacent bridge arms of the Wheatstone full bridge structure in the magnetic sensor change oppositely with the external magnetic field, which means that the two adjacent magnetoresistance units constituting the bridge arm should have opposite magnetic pinning directions.

[0003] In the prior art, the magnetoresistance units on two adjacent bridge arms of the Wheatstone full bridge structure in the magnetic sensor have opposite magnetic pinning directions by the following methods: the first method is a mechanical assembly method, in which the magnetoresistance units on the adjacent bridge arms are relatively rotated 180 degrees, and the magnetoresistance units are wire bonded; the second method is to achieve local annealing by current or radiation to change the pinning direction of the magnetoresistance units on the bridge arms; the third method is to deposit thin films of different structures on the same wafer in different areas so that their pinning directions are opposite; the fourth method is to bend the magnetic flux lines through a magnetic flux concentrator structure so that the external magnetic field detected by the magnetoresistance units on the adjacent bridge arms is opposite. However, the above methods are difficult to achieve accurate and efficient control, and it is difficult to ensure that the magnetic pinning directions of the magnetoresistance units on the two adjacent bridge arms of the Wheatstone full bridge structure are completely opposite, and the process is relatively complex, the preparation cost is high, the performance consistency of the magnetoresistance units is poor, and the volume of the magnetic sensor is increased, which is not conducive to miniaturization. Summary of the invention

[0004] The first object of the present invention is to provide a method for preparing a magnetic sensor, so as to control the magnetoresistive unit to rotate 180 degrees relative to each other, so as to satisfy the requirement that the magnetoresistive units on two adjacent bridge arms of the Wheatstone full bridge structure have opposite magnetic pinning directions, thereby improving the stability of the magnetic sensor performance. Another object of the present invention is to provide a magnetic sensor. The second object of the present invention is to provide a dual-axis magnetic sensor. The third object of the present invention is to provide a tri-axis magnetic sensor.

[0005] In order to achieve the above objectives, the present invention discloses a method for preparing a magnetic sensor, the method comprising: etching a first substrate to form a first protrusion; forming a second substrate on the first substrate after etching, the second substrate having a first recess corresponding to the first protrusion; forming a first magnetic resistor, a second magnetic resistor, a third magnetic resistor and a fourth magnetic resistor connected in a full bridge on the second substrate, wherein the first magnetic resistor, the second magnetic resistor, the third magnetic resistor and the fourth magnetic resistor have the same pinning direction, the first magnetic resistor is electrically connected to one end of the second magnetic resistor and the fourth magnetic resistor respectively, the third magnetic resistor is electrically connected to the other end of the second magnetic resistor and the fourth magnetic resistor respectively, the first magnetic resistor and the third magnetic resistor are located on one side of the first recess, and the second magnetic resistor and the fourth magnetic resistor are located on the other side of the first recess; peeling off the first substrate to obtain a magnetic sensor body; folding the magnetic sensor body along the first recess so that the pinning directions of the first magnetic resistor and the third magnetic resistor are opposite to the pinning directions of the second magnetic resistor and the fourth magnetic resistor.

[0006] Preferably, the method further comprises: determining a folding line in the first recess; and folding the magnetic sensor body along the first recess comprises: folding the magnetic sensor body along the folding line.

[0007] Preferably, determining the folding line in the first recess includes: determining the folding line at the thinnest part of the first recess.

[0008] Preferably, the thickness of the first recess at its thinnest point is less than one third of the thickness of the second substrate.

[0009] Preferably, folding the magnetic sensor body along the folding line comprises: folding the magnetic sensor body on one side of the first recess along the folding line to above or below the magnetic sensor body on the other side of the first recess.

[0010] Preferably, the first magnetoresistance, the second magnetoresistance, the third magnetoresistance and the fourth magnetoresistance forming a full-bridge connection on the second substrate include: forming four bottom electrodes of the magnetoresistance on the second substrate, the bottom electrodes including a first bottom electrode shared by the first magnetoresistance and the second magnetoresistance and a second bottom electrode shared by the third magnetoresistance and the fourth magnetoresistance; forming four magnetoresistances on the bottom electrodes respectively; forming top electrodes on the four magnetoresistances respectively; forming external electrodes, the external electrodes including a first excitation electrode, a first output electrode, a second excitation electrode and a second output electrode, the first bottom electrode being electrically connected to the first excitation electrode, the second bottom electrode being electrically connected to the second excitation electrode, the top electrode shared by the second magnetoresistance and the third magnetoresistance being electrically connected to the first output electrode, and the top electrode shared by the first magnetoresistance and the fourth magnetoresistance being electrically connected to the second output electrode.

[0011] Preferably, forming four bottom electrodes of the magnetoresistance on the second substrate comprises: depositing a first conductive material on the second substrate; and patterning the first conductive material to form four bottom electrodes of the magnetoresistance.

[0012] Preferably, forming four magnetic resistors respectively on the bottom electrode includes: depositing magnetic material on the second substrate; and patterning the magnetic material at positions corresponding to the bottom electrode or the top electrode to form the first magnetic resistor, the second magnetic resistor, the third magnetic resistor and the fourth magnetic resistor.

[0013] Preferably, forming top electrodes on the four magnetoresistors respectively includes: depositing a dielectric layer on the first magnetoresistors, the second magnetoresistors, the third magnetoresistors, the fourth magnetoresistors and the bottom electrode connected in a full bridge; and forming a top electrode on the dielectric layer.

[0014] Preferably, forming the top electrode on the dielectric layer includes: patterning the dielectric layer above the first magnetic resistor, the second magnetic resistor, the third magnetic resistor, and the fourth magnetic resistor to form a through hole; depositing a second conductive material on the dielectric layer forming the through hole; and patterning the second conductive material to form the top electrode.

[0015] Preferably, the method further comprises: forming a protective layer on the top electrode.

[0016] Preferably, forming the second substrate on the first substrate after the etching process comprises: forming a sacrificial layer on the first substrate after the etching process; and forming the second substrate on the sacrificial layer.

[0017] Preferably, the second substrate is made of a flexible material.

[0018] The invention also discloses a magnetic sensor, which is prepared by the above-mentioned method for preparing the magnetic sensor.

[0019] The present invention also discloses a dual-axis magnetic sensor, comprising two stacked magnetic sensors, at least one of which is prepared by the above-mentioned method for preparing a magnetic sensor; wherein the magnetic sensitive directions of the two magnetic sensors are arranged orthogonally in a plane.

[0020] The present invention also discloses a three-axis magnetic sensor, comprising a stacked first magnetic sensor, a second magnetic sensor and a third magnetic sensor, at least one of which is prepared by the above-mentioned method for preparing a magnetic sensor; wherein the magnetic sensitive directions of the first magnetic sensor and the second magnetic sensor are arranged orthogonally within a plane, and the magnetic sensitive direction of the third magnetic sensor is arranged out of the plane and orthogonally to the magnetic sensitive directions of the first magnetic sensor and the second magnetic sensor.

[0021] The magnetic sensor prepared by the embodiment of the present invention folds the magnetic sensor body along the first recess to achieve the folding of two adjacent magnetoresistive elements, thereby better controlling the relative rotation of the two adjacent magnetoresistive elements by 180 degrees, so as to better meet the requirement that the magnetoresistive units on the two adjacent bridge arms of the Wheatstone full bridge structure have opposite magnetic pinning directions, thereby improving the stability of the magnetic sensor performance. In addition, the magnetoresistive elements are formed through a one-time process, and the magnetoresistive characteristics are the same, ensuring the consistency of magnetoresistive. Moreover, compared with the existing methods of passing current, radiation, partitioned deposition, and adding additional devices, the above-mentioned folding method is relatively simple in process and precisely controlled, thereby simplifying the preparation process of the magnetic sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 One of the flow charts showing a specific embodiment of a method for preparing a magnetic sensor of the present invention;

[0024] Figure 2 A flow chart showing a method for preparing a magnetic sensor according to a specific embodiment of the present invention for forming a second substrate on an etching-treated first substrate;

[0025] Figure 3 A flow chart showing a method for preparing a magnetic sensor according to a specific embodiment of the present invention, wherein a first magnetoresistance, a second magnetoresistance, a third magnetoresistance and a fourth magnetoresistance are formed on a second substrate in a full-bridge connection;

[0026] Figure 4 A circuit diagram of a first magnetoresistance, a second magnetoresistance, a third magnetoresistance and a fourth magnetoresistance connected in a full bridge in a specific embodiment of a method for preparing a magnetic sensor of the present invention is shown;

[0027] Figure 5 A flowchart showing a method for preparing a magnetic sensor according to a specific embodiment of the present invention, in which top electrodes are formed on four magnetic resistors respectively;

[0028] Figure 6 A second flowchart showing a specific embodiment of a method for preparing a magnetic sensor of the present invention;

[0029] Figure 7 A third flowchart showing a specific embodiment of a method for preparing a magnetic sensor of the present invention;

[0030] Figure 8 A structural diagram showing a first substrate with a first protrusion in a specific embodiment of a method for preparing a magnetic sensor of the present invention;

[0031] Fig. 9 A structural diagram of a device after a sacrificial layer is deposited in a specific embodiment of a method for preparing a magnetic sensor of the present invention is shown;

[0032] Fig.10 A structural diagram of a device after a solidified layer is formed on a sacrificial layer in a specific embodiment of a method for preparing a magnetic sensor of the present invention;

[0033] Fig.11 A structural diagram of a device after a bottom electrode and four magnetoresistors on the bottom electrode are formed on a second substrate in a specific embodiment of a method for preparing a magnetic sensor of the present invention;

[0034] Fig.12 A structural diagram of a device after a dielectric layer is formed on four magnetoresistors and a bottom electrode in a specific embodiment of a method for preparing a magnetic sensor of the present invention;

[0035] Fig.13 A structural diagram of a device after a top electrode and an external electrode are formed on a dielectric layer in a specific embodiment of a method for preparing a magnetic sensor of the present invention;

[0036] Fig.14 A structural diagram of a device after a protective layer is formed on a top electrode in a specific embodiment of a method for preparing a magnetic sensor of the present invention is shown;

[0037] Fig.15 A structural diagram of a magnetic sensor body in a specific embodiment of a method for preparing a magnetic sensor of the present invention is shown;

[0038] Fig.16 A structural diagram of a magnetic sensor in a specific embodiment of a method for preparing a magnetic sensor of the present invention is shown. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] In the prior art, the magnetoresistive units on two adjacent bridge arms of the Wheatstone full bridge structure in the magnetic sensor have opposite magnetic pinning directions by:

[0041] The first is a mechanical assembly method, which is to rotate the magnetoresistive units of adjacent bridge arms by 180 degrees relative to each other and bond the magnetoresistive units together through wire bonding. However, this method is difficult to ensure the accuracy of the rotation angle, and it is also impossible to meet the requirement that the magnetic pinning directions of the magnetoresistive units on the two adjacent bridge arms of the Wheatstone full bridge structure are completely opposite.

[0042] The second method is to achieve local annealing through current or radiation to change the pinning direction of the magnetoresistive unit on the bridge arm, but this method is inefficient and complex in process and is not suitable for large-scale mass production.

[0043] The third method is to deposit thin films of different structures in different areas on the same wafer so that their pinning directions are opposite. This method requires two thin film depositions, which increases the process difficulty and cost, and it is difficult to ensure that the magnetoresistance performance of the two thin film structures is consistent.

[0044] The fourth method is to bend the magnetic flux lines through a flux concentrator structure so that the external magnetic fields detected by the magnetoresistive units on adjacent bridge arms are in opposite directions. It can be seen that this method requires additional devices, resulting in increased costs and complex processes.

[0045] From the above content, it can be seen that the existing method of realizing that the magnetoresistance units on two adjacent bridge arms of the Wheatstone full bridge structure in the magnetic sensor have completely opposite magnetic pinning directions cannot well control the relative rotation of the magnetoresistance units by 180 degrees, and cannot satisfy the requirement that the magnetoresistance units on two adjacent bridge arms of the Wheatstone full bridge structure have opposite magnetic pinning directions, resulting in low stability of the magnetic sensor performance and relatively complex process.

[0046] In view of the problems of magnetic sensors in the prior art, the present invention proposes a method for preparing a magnetic sensor, by folding the magnetic sensor body on one side of a first recess along a folding line to the magnetic sensor body on the other side of the first recess, so as to better control the relative rotation of two adjacent magnetoresistive units by 180 degrees, thereby better satisfying the requirement that the magnetoresistive units on two adjacent bridge arms in the Wheatstone full-bridge structure have opposite pinning directions, thereby improving the stability of the magnetic sensor performance, and the folding method is relatively simple compared to the existing methods of passing current, radiation, partitioned deposition and adding additional devices, thereby simplifying the preparation process of the magnetic sensor.

[0047] In order to solve the above problems, according to one aspect of the present invention, this embodiment discloses a method for preparing a magnetic sensor. Figure 1 As shown, the preparation method of the magnetic sensor includes:

[0048] S100: etching the first substrate to form a first protrusion.

[0049] In the embodiment of the present invention, the first protrusion may be in any shape. Preferably, the shape of the first protrusion may be a trapezoid.

[0050] Preferably, the first substrate may be single crystal silicon, and anisotropic wet etching is used to etch the first substrate to form a raised interface with high flatness and a precisely controllable shape.

[0051] S200: forming a second substrate on the first substrate after the etching process, wherein the second substrate has a first recess corresponding to the first protrusion.

[0052] Preferably, the second substrate is a flexible material. The embodiment of the present invention does not specifically limit the material of the second substrate, but all flexible materials that can be used as substrates are within the protection scope of the present invention. For example, the second substrate can be polyimide (PI).

[0053] By setting the material of the second substrate to be a flexible material, the subsequent folding operation is facilitated, thereby simplifying the preparation method of the magnetic sensor.

[0054] In addition, the embodiment of the present invention does not limit whether the interior of the first recess is horizontal or whether there is a weakest point. If the interior of the first recess is horizontal, then the thickness of the first recess is less than the first preset thickness. If the first recess is not horizontal, then there will be a weakest point inside, and the thickness of the thinnest part of the first recess is less than the second preset thickness. The first preset thickness and the second preset thickness here may be the same or different, and the specific value can be set according to the flexibility of the first substrate and the specific application scenario, which is not limited by the embodiment of the present invention. For example, the first preset thickness and the second preset thickness are the same, which is one-third of the thickness of the second substrate.

[0055] S300: forming a first magnetic resistor, a second magnetic resistor, a third magnetic resistor and a fourth magnetic resistor which are fully bridge-connected on a second substrate.

[0056] In this embodiment, the pinning directions of the first magnetic resistor, the second magnetic resistor, the third magnetic resistor and the fourth magnetic resistor are the same, the first magnetic resistor is electrically connected to one end of the second magnetic resistor and the fourth magnetic resistor respectively, the third magnetic resistor is electrically connected to the other end of the second magnetic resistor and the fourth magnetic resistor respectively, the first magnetic resistor is adjacent to the second magnetic resistor, and the third magnetic resistor is adjacent to the fourth magnetic resistor.

[0057] The two adjacent magnetic resistors are distributed on both sides of the first recess. Further, based on the above adjacent relationship (i.e., the first magnetic resistor and the second magnetic resistor are adjacent, and the third magnetic resistor and the fourth magnetic resistor are adjacent), it can be determined that the first magnetic resistor and the third magnetic resistor are located on one side of the first recess, and the second magnetic resistor and the fourth magnetic resistor are located on the other side of the first recess. For example, the first magnetic resistor and the third magnetic resistor are located on the left side of the first recess, and the second magnetic resistor and the fourth magnetic resistor are located on the right side of the first recess, or the first magnetic resistor and the third magnetic resistor are located on the right side of the first recess, and the second magnetic resistor and the fourth magnetic resistor are located on the left side of the first recess.

[0058] S400: peeling off the first substrate to obtain a magnetic sensor body.

[0059] S500: Folding the magnetic sensor body in half along the first recess, so that the pinning directions of the first and third magnetic resistors are opposite to the pinning directions of the second and fourth magnetic resistors.

[0060] Specifically, the magnetic sensor body on one side of the first recess is folded along the first recess to the top or bottom of the magnetic sensor body on the other side of the first recess, so that the pinning directions of two adjacent magnetic resistors are opposite, and further, the pinning directions of the first magnetic resistor, the third magnetic resistor, the second magnetic resistor, and the fourth magnetic resistor are opposite.

[0061] Specifically, when the first and third magnetic resistors are located on the left side of the first recess and the second and fourth magnetic resistors are located on the right side of the first recess, the magnetic sensor body on the left side of the first recess can be folded upward along the first recess to above the magnetic sensor body on the right side of the first recess.

[0062] The present invention arranges adjacent magnetic resistors on both sides of a first recess and folds the magnetic sensor body along the first recess to achieve folding of two adjacent magnetic resistor elements, thereby better controlling the relative rotation of the two adjacent magnetic resistor elements by 180 degrees, thereby better satisfying the requirement that the magnetic resistor units on the two adjacent bridge arms of the Wheatstone full bridge structure have opposite pinning directions, thereby improving the stability of the magnetic sensor performance.

[0063] The magnetoresistive element of the present invention is formed through a one-time process, has the same magnetoresistive characteristics, and ensures the consistency of magnetoresistive.

[0064] Compared with the existing methods of current, radiation, partitioned deposition and adding additional devices, the above-mentioned folding method is relatively simple, thereby simplifying the preparation process of the magnetic sensor. And because the second substrate is a flexible material, the magnetic sensor body can be folded in half more conveniently, further simplifying the preparation process of the magnetic sensor.

[0065] As an optional implementation, Figure 2 As shown, the S200 may specifically include:

[0066] S210: forming a sacrificial layer on the first substrate after the etching process.

[0067] The embodiment of the present invention does not impose any specific restrictions on the material of the sacrificial layer, but the materials of the sacrificial layer in the prior art are all within the protection scope of the embodiment of the present invention. For example, the material of the sacrificial layer may be silicon oxide, organic polymer, etc.

[0068] When a sacrificial layer is formed on the first substrate, S400 includes: peeling off the first substrate and the sacrificial layer to obtain the magnetic sensor body.

[0069] S220: Spin-coat PI on the sacrificial layer and solidify to obtain a second substrate.

[0070] Spin coating PI on the sacrificial layer and curing it on the second substrate includes: spin coating PI solution on the sacrificial layer and heating and curing it to form a PI solid film, and the PI solid film serves as the second substrate.

[0071] It is worth noting that the bottom electrode and the top electrode have the same function and play the role of connecting four magnetic resistors. The positions of the bottom electrode and the top electrode can be interchanged, that is, if the bottom electrode is set first, then the top electrode is set later, and if the top electrode is set first, then the bottom electrode is set later. In a preferred embodiment, Figure 3 As shown, taking the example of first setting the bottom electrode and then setting the top electrode, the S300 may specifically include:

[0072] S310: forming four bottom electrodes of the magnetoresistors on the second substrate, the bottom electrodes comprising a first bottom electrode and a second bottom electrode, a first bottom electrode shared by the first magnetoresistors and the second magnetoresistors, and a second bottom electrode shared by the third magnetoresistors and the fourth magnetoresistors.

[0073] Specifically, a first conductive material is deposited on the second substrate, and the first conductive material is patterned to form four bottom electrodes of the magnetoresistor. The patterning process here includes photolithography, etching and other processes.

[0074] S320: Four magnetoresistors are formed on the bottom electrode respectively. Specifically, a magnetic material is deposited on the bottom electrode, and a first magnetoresistor, a second magnetoresistor, a third magnetoresistor and a fourth magnetoresistor are formed by etching the magnetic material at positions corresponding to the bottom electrode.

[0075] S330: forming top electrodes on the four magnetic resistors respectively.

[0076] S340: forming external electrodes. The external electrodes include a first excitation electrode V DD , the second excitation electrode GND, the first output electrode V+ and the second output electrode V-. The first bottom electrode and the first excitation electrode V DD The second bottom electrode is electrically connected to the second excitation electrode GND, the top electrode shared by the second magnetic resistor and the third magnetic resistor is electrically connected to the first output electrode V+, and the top electrode shared by the first magnetic resistor and the fourth magnetic resistor is electrically connected to the second output electrode V-.

[0077] Thus, the circuit of the first magnetic resistance, the second magnetic resistance, the third magnetic resistance and the fourth magnetic resistance connected in a full bridge is obtained as follows: Figure 4 shown. Figure 4 1, 2, 3, and 4 represent the first magnetic resistance, the second magnetic resistance, the third magnetic resistance, and the fourth magnetic resistance, respectively.

[0078] In a preferred embodiment, Figure 5 As shown, taking the example of first setting the bottom electrode and then setting the top electrode, the S330 may specifically include:

[0079] S3310: depositing a dielectric layer on the first magnetic resistor, the second magnetic resistor, the third magnetic resistor, the fourth magnetic resistor and the bottom electrode connected in the full bridge.

[0080] In this embodiment, the dielectric layer is used for insulation to prevent components that are not electrically connected from being electrically connected. The material of the dielectric layer includes insulating materials, and the insulating materials include silicon nitride, silicon dioxide, and the like.

[0081] S3320: Patterning the dielectric layer above the first magnetic resistor, the second magnetic resistor, the third magnetic resistor, and the fourth magnetic resistor to form through holes.

[0082] S3330: depositing a second conductive material on the dielectric layer forming the through-hole, and patterning the second conductive material at positions corresponding to the four magnetic resistors to form a top electrode.

[0083] In an optional implementation, S340 includes: depositing a third conductive material on the second conductive material, and etching the third conductive material to form an external electrode.

[0084] The first conductive material, the second conductive material and the third conductive material can be selected according to the actual application scenario, and the embodiment of the present invention does not limit this. For example, the first conductive material, the second conductive material and the third conductive material are the same, and can be metal, conductive plastic, conductive rubber, etc., or conductive composite materials.

[0085] In order to solve the above problems, according to another aspect of the present invention, this embodiment discloses a method for preparing a magnetic sensor. Figure 6 As shown, the method for preparing the magnetic sensor includes S100 to S400, S600 and S700. In this embodiment, S100 to S400 and Figure 1 The corresponding embodiments are similar and will not be described again here.

[0086] S600: Determine a folding line in the first recess.

[0087] If there is a weakest point in the first depression, the folding line is determined at the thinnest point of the first depression. If there is no weakest point in the first depression, the folding line is determined at any position of the first depression, preferably, the middle position of the first depression.

[0088] S700: Folding the magnetic sensor body along the folding line. Specifically, folding the magnetic sensor body on one side of the first recess along the folding line to the top or bottom of the magnetic sensor body on the other side of the first recess.

[0089] In this embodiment, when the first magnetic resistor and the third magnetic resistor are located on the left side of the first recess, and the second magnetic resistor and the fourth magnetic resistor are located on the right side of the first recess, the magnetic sensor body on the left side of the first recess can be folded upward along the folding line to the top of the magnetic sensor body on the right side of the first recess. The folding line of the magnetic sensor body on the right side of the first recess can also be folded downward to the bottom of the magnetic sensor body on the left side of the first recess, but in this case, the first recess needs to be large enough so that when folded downward, the second magnetic resistor can be ensured to be below the first magnetic resistor and the fourth magnetic resistor can be below the third magnetic resistor.

[0090] The present invention determines the folding line at the thinnest part of the first depression, so that the thickness of the substrate at the folding line becomes thinner, or determines the folding line at the middle position of the first depression, thereby making it easier to completely fold the magnetic sensor body along the folding line, realizing a high-precision alignment design, and more accurately controlling the relative rotation of two adjacent magnetoresistive elements by 180 degrees, so that the magnetoresistive units on the two adjacent bridge arms of the Wheatstone full-bridge structure have opposite magnetic pinning directions, thereby further improving the stability of the magnetic sensor performance.

[0091] The magnetoresistive element of the embodiment of the present invention is formed through a one-time process, has the same magnetoresistive characteristics, and ensures the consistency of magnetoresistive.

[0092] Compared with the existing methods of current, radiation, partition deposition and adding additional devices, the above folding method is relatively simple, thereby simplifying the preparation process of the magnetic sensor. And because the second substrate is a flexible material, the magnetic sensor body can be folded in half more conveniently, further simplifying the preparation process of the magnetic sensor.

[0093] The present application is further described below through a specific example. Figure 7 As shown, in this specific example, the bottom electrode is prepared first and then the top electrode is prepared. The preparation method of the magnetic sensor includes the following steps:

[0094] S100: Etching the first substrate to form a first protrusion. Taking the shape of the first protrusion as a trapezoid as an example, the first substrate 100 with the first protrusion is as follows: Figure 8 shown.

[0095] S210: forming a sacrificial layer 200 on the first substrate after the etching process, and the device after the sacrificial layer 200 is deposited is as follows: Fig. 9 shown.

[0096] S220: Spin-coating PI on the sacrificial layer and curing to obtain a second substrate 300. After the second substrate 300 is formed on the sacrificial layer, the device is as follows: Fig.10 shown.

[0097] S310: forming four bottom electrodes 400 of the magnetoresistor on the second substrate, that is, forming four bottom electrodes of the magnetoresistor on the solidified layer of the second substrate.

[0098] S320: Four magnetic resistors 500 are formed on the bottom electrodes. After the bottom electrode 400 and the four magnetic resistors 500 on the bottom electrode are formed on the second substrate 300, the device is as follows: Fig.11 shown.

[0099] S3310: depositing a dielectric layer 600 on the first magnetic resistor, the second magnetic resistor, the third magnetic resistor, the fourth magnetic resistor and the bottom electrode connected in the full bridge, and forming a device after the dielectric layer 600 is formed on the four magnetic resistors and the bottom electrode. Fig.12 shown.

[0100] S3320: Patterning the dielectric layer above the first magnetic resistor, the second magnetic resistor, the third magnetic resistor, and the fourth magnetic resistor to form through holes.

[0101] S3330: depositing a second conductive material on the dielectric layer 600 where the through hole is formed, and patterning the second conductive material to form a top electrode 700.

[0102] S340: forming an external electrode 800. After forming the top electrode and the external electrode on the dielectric layer, the device is as follows Fig.13 shown.

[0103] S800: forming a protective layer 900 on the top electrode. After the protective layer is formed on the top electrode, the device is as follows Fig.14 shown.

[0104] The protective layer may be a flexible protective layer, and the material of the protective layer may include polyimide, polyurethane, polypropylene, composite polymer, etc. The protective layer protects the circuit from being affected by the external environment (such as moisture, foreign impurities, mechanical damage, etc.), thereby protecting the magnetic sensor.

[0105] S400: peeling off the first substrate and the sacrificial layer to obtain a magnetic sensor body. The magnetic sensor body is as follows: Fig.15 As shown, the magnetic sensor body includes a second substrate 300 , a bottom electrode layer 400 , a magnetoresistor 500 , a dielectric layer 600 , a top electrode 700 , an external electrode 800 , and a protective layer 900 .

[0106] S600: Determine a folding line in the first recess.

[0107] S700: Folding the magnetic sensor body along the folding line to obtain a magnetic sensor, such as Fig.16 shown.

[0108] The present invention folds the magnetic sensor body along the folding line to achieve high-precision satisfaction. The magnetoresistance units on two adjacent bridge arms of the Wheatstone full-bridge structure have opposite magnetic pinning directions, thereby improving the stability of the magnetic sensor performance. At the same time, the protective layer protects the circuit from being affected by the external environment, thereby protecting the magnetic sensor and improving the durability of the magnetic sensor.

[0109] The magnetoresistive element of the embodiment of the present invention is formed through a one-time process, has the same magnetoresistive characteristics, and ensures the consistency of magnetoresistive.

[0110] Compared with the existing methods of current, radiation, partition deposition and adding additional devices, the above folding method is relatively simple, thereby simplifying the preparation process of the magnetic sensor. And because the second substrate is a flexible material, the magnetic sensor body can be folded in half more conveniently, further simplifying the preparation process of the magnetic sensor.

[0111] The present invention also provides a magnetic sensor, which is prepared by the above-mentioned magnetic field sensor preparation method. Fig.16 shown.

[0112] The present invention also provides a dual-axis magnetic sensor, comprising a stacked first magnetic sensor and a second magnetic sensor, wherein at least one magnetic sensor is prepared by the above-mentioned method for preparing a magnetic sensor. The stacking method includes: the magnetic sensitive directions of the two magnetic sensors are arranged orthogonally in a plane, and specifically, the first magnetic sensor is stacked on the second magnetic sensor in a manner that the magnetic sensitive directions are perpendicular in the plane.

[0113] The present invention further provides a three-axis magnetic sensor, which includes a stacked first magnetic sensor, a second magnetic sensor, and a third magnetic sensor, at least one of which is prepared by the above-mentioned method for preparing a magnetic sensor. The stacking method includes: the magnetic sensitive directions of the first magnetic sensor and the second magnetic sensor are arranged orthogonally in the plane, and the magnetic sensitive direction of the third magnetic sensor is arranged out of the plane and orthogonal to the magnetic sensitive directions of the first magnetic sensor and the second magnetic sensor. Specifically, the first magnetic sensor is first stacked on the second magnetic sensor in a manner that the magnetic sensitive direction is perpendicular to the plane, and secondly, the magnetic sensitive direction of the third magnetic sensor is stacked on the second magnetic sensor in a manner that the magnetic sensitive direction is out of the plane and perpendicular to the magnetic sensitive direction of the second magnetic sensor.

[0114] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0115] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0116] The above is only an 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 changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A method for preparing a magnetic sensor, characterized in that: The preparation method comprises: Etching the first substrate to form a first protrusion; forming a second substrate on the first substrate after the etching process, wherein the second substrate has a first depression corresponding to the first protrusion; A first magnetic resistor, a second magnetic resistor, a third magnetic resistor and a fourth magnetic resistor are formed on the second substrate, wherein the first magnetic resistor, the second magnetic resistor, the third magnetic resistor and the fourth magnetic resistor have the same pinning direction, the first magnetic resistor is electrically connected to one end of the second magnetic resistor and the fourth magnetic resistor respectively, the third magnetic resistor is electrically connected to the other end of the second magnetic resistor and the fourth magnetic resistor respectively, the first magnetic resistor and the third magnetic resistor are located on one side of the first recess, and the second magnetic resistor and the fourth magnetic resistor are located on the other side of the first recess; Peeling off the first substrate to obtain a magnetic sensor body; The magnetic sensor body is folded in half along the first recess so that the pinning directions of the first magnetic resistor and the third magnetic resistor are opposite to the pinning directions of the second magnetic resistor and the fourth magnetic resistor.

2. The preparation method according to claim 1, characterized in that The method further comprises: defining a fold line within the first recess; The step of folding the magnetic sensor body in half along the first recess comprises: The magnetic sensor body is folded in half along the folding line.

3. The preparation method according to claim 2, characterized in that: Determining a folding line in the first recess comprises: The fold line is defined at the thinnest point of the first depression.

4. The preparation method according to claim 3, characterized in that: The thickness of the first recess at its thinnest point is less than one third of the thickness of the second substrate.

5. The preparation method according to any one of claims 2 to 4, characterized in that: The step of folding the magnetic sensor body along the folding line comprises: The magnetic sensor body at one side of the first recess is folded along the folding line to the upper side or the lower side of the magnetic sensor body at the other side of the first recess.

6. The preparation method according to any one of claims 1 to 4, characterized in that The first magnetic resistor, the second magnetic resistor, the third magnetic resistor and the fourth magnetic resistor forming a full-bridge connection on the second substrate include: Forming four bottom electrodes of magnetic resistors on the second substrate, the bottom electrodes comprising a first bottom electrode shared by the first magnetic resistor and the second magnetic resistor and a second bottom electrode shared by the third magnetic resistor and the fourth magnetic resistor; forming four magnetic resistors on the bottom electrode respectively; forming top electrodes on the four magnetic resistors respectively; External electrodes are formed, and the external electrodes include a first excitation electrode, a first output electrode, a second excitation electrode, and a second output electrode. The first bottom electrode is electrically connected to the first excitation electrode, the second bottom electrode is electrically connected to the second excitation electrode, the top electrode shared by the second magnetic resistor and the third magnetic resistor is electrically connected to the first output electrode, and the top electrode shared by the first magnetic resistor and the fourth magnetic resistor is electrically connected to the second output electrode.

7. The preparation method according to claim 6, characterized in that: The bottom electrodes of four magnetoresistors are formed on the second substrate, comprising: depositing a first conductive material on the second substrate; The first conductive material is patterned to form four bottom electrodes of the magnetoresistor.

8. The preparation method according to claim 6, characterized in that: The forming of four magnetic resistors on the bottom electrode comprises: depositing a magnetic material on the second substrate; Patterning is performed on the magnetic material at a position corresponding to the bottom electrode to form the first magnetic resistor, the second magnetic resistor, the third magnetic resistor and the fourth magnetic resistor.

9. The preparation method according to claim 6, characterized in that: The forming of top electrodes on the four magnetic resistors respectively comprises: Depositing a dielectric layer on the first magnetic resistor, the second magnetic resistor, the third magnetic resistor, the fourth magnetic resistor and the bottom electrode connected in a full bridge; A top electrode is formed on the dielectric layer.

10. The preparation method according to claim 9, characterized in that: The forming of a top electrode on the dielectric layer comprises: Patterning the dielectric layer above the first magnetic resistor, the second magnetic resistor, the third magnetic resistor, and the fourth magnetic resistor to form a through hole; Depositing a second conductive material on the dielectric layer forming the through hole; The top electrode is formed by patterning the second conductive material.

11. The preparation method according to claim 10, characterized in that: The method further comprises: A protection layer is formed on the top electrode.

12. The preparation method according to any one of claims 1 to 4, characterized in that: The forming of the second substrate on the first substrate after the etching process comprises: forming a sacrificial layer on the first substrate after the etching process; The second substrate is formed on the sacrificial layer.

13. The preparation method according to any one of claims 1 to 4, characterized in that: The second substrate is made of flexible material.

14. A magnetic sensor, characterized in that: The magnetic sensor is prepared by the method for preparing the magnetic sensor according to any one of claims 1 to 13.

15. A dual-axis magnetic sensor, characterized in that: Comprising two stacked magnetic sensors, at least one of the magnetic sensors is prepared by the method for preparing a magnetic sensor according to any one of claims 1 to 13; Wherein, the magnetic sensitive directions of the two magnetic sensors are arranged orthogonally.

16. A three-axis magnetic sensor, characterized in that: comprising a first magnetic sensor, a second magnetic sensor and a third magnetic sensor which are stacked, at least one magnetic sensor being prepared by the method for preparing a magnetic sensor according to any one of claims 1 to 13; The magnetic sensitive directions of the first magnetic sensor and the second magnetic sensor are arranged orthogonally in the plane, and the magnetic sensitive direction of the third magnetic sensor is arranged out of the plane and orthogonally to the magnetic sensitive directions of the first magnetic sensor and the second magnetic sensor.

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