360-degree non-blind area micro angular displacement magnetic probe chip, preparation method and application

Abstract

The invention relates to the technical field of electrical machinery, in particular to a 360-degree non-blind area micro angular displacement magnetic probe chip, a preparation method and application. The chip comprises the following components from bottom to top: a substrate which is a traditional silicon substrate wafer; the AMR thin film structure comprises a seed layer, an AMR magnetic functional layer and a protective layer; the insulating medium layer is used for electrical insulation between different metal layers; an AHE thin film layer, wherein the AHE thin film structure is a buffer layer / an active layer / a covering layer; by integrating an anisotropic magnetoresistance (AMR) element and an anomalous Hall effect (AHE) element on one chip, the uniqueness detection of any angle within the range of 0-360 degrees can be realized. The AMR element is responsible for high-precision measurement within the range of 0-180 degrees, and the AHE element is used for judging the polarity of a magnetic field, so that the problem that a traditional AMR sensor can only detect 0-180 degrees is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic sensors, and in particular to a 360-degree blind-zone-free miniature angular displacement magnetic probe chip, a preparation method and an application thereof. Background Art

[0002] In the development process of high-precision angular displacement sensing technology, it is found that non-contact angular displacement sensing technology is not prone to wear during the measurement process, has good durability and high reliability, and is more suitable for application in the fields of industry, green energy, aerospace, aviation, etc. Angular displacement sensing technology based on the principles of optics, electricity and magnetism is the most common non-contact angular displacement sensor design method on the market.

[0003] Optical sensing technology: The mechanical structure of this technology is relatively complex, the operation is inconvenient, and its adaptability in harsh environments is poor.

[0004] Electrical sensing technology: low resolution, poor stability and insufficient accuracy.

[0005] Magnetic sensing technology: Magnetic sensing technology that obtains angular displacement information by sensing magnetic field changes can overcome the above shortcomings. It has the advantages of simple unit mechanical structure, strong adaptability to harsh environments, anti-vibration, anti-noise, etc., and has high resolution, good operating stability and low cost. Therefore, magnetic sensing technology based on the principle of magnetic signal detection has gradually become the mainstream choice in the market.

[0006] Magnetoresistive angular displacement sensing technology has attracted much attention due to its advantages such as high precision, miniaturization, integration, and low power consumption. It is mainly divided into the following types:

[0007] Anisotropic magnetoresistive (AMR) angular displacement sensing: Limited by the generation mechanism of the AMR effect, traditional AMR angular displacement sensing technology can only achieve angular displacement detection of 0 to 180 degrees at most. In order to achieve 360-degree angular displacement detection without blind spots, additional magnetic field polarity determination methods such as Hall devices and TMR unipolar switching devices must be used. However, this combination has low integration and high power consumption, which is not conducive to the miniaturization and low power consumption of electronic components.

[0008] Giant magnetoresistance (GMR) angular displacement sensing and tunnel magnetoresistance (TMR) angular displacement sensing: These two technologies can directly achieve 360-degree angular displacement detection, but they have problems such as large hysteresis and high noise, complex preparation process, high technical requirements, high cost, and their stability is not as good as AMR angular displacement sensing technology.

[0009] In summary, the existing magnetic angular displacement sensors still have room for improvement in terms of integration, preparation process, stability and detection accuracy. Summary of the invention

[0010] The present invention provides a 360-degree blind-zone-free miniature angular displacement magnetic probe chip, a preparation method and an application thereof, the purpose of which is to improve the integration, preparation process flow, stability and detection accuracy of existing magnetic sensitive angular displacement sensors, and to provide a better solution for 360-degree blind-zone-free angular displacement detection.

[0011] To achieve the above object, the technical solution of the present invention is:

[0012] A miniature angular displacement magnetic probe chip for 360-degree blind spot detection, the chip comprising from bottom to top:

[0013] Substrate, the substrate is a traditional silicon-based wafer, with several hundred nanometers of SiO2 oxidized on Si;

[0014] AMR film layer, wherein the AMR film structure is a seed layer / AMR magnetic functional layer / protective layer, wherein the AMR magnetic functional layer is made of a soft magnetic metal alloy material such as NiFe or NiCo with low hysteresis, small saturation field, high magnetic permeability, and high Curie temperature;

[0015] Insulating dielectric layer, used for electrical insulation between different metal layers;

[0016] An AHE thin film layer, wherein the AHE thin film structure is a buffer layer / active layer / covering layer, and the active layer is used to generate an anomalous Hall effect to achieve a magnetic field polarity discrimination function;

[0017] The passivation layer is used to protect the magnetic thin film components from the influence of the external environment during electrical testing, packaging and use.

[0018] Furthermore, the AMR film layer adopts a double saturated Wheatstone bridge structure, each Wheatstone bridge is composed of four groups of magnetoresistive strip arrays placed at 90 degrees to each other, so as to improve parameter indicators such as sensitivity, signal-to-noise ratio, and temperature stability.

[0019] Furthermore, the AHE thin film layer is designed to be a Hall bar in the shape of a cross, which is used to distinguish the polarity of the magnetic field to achieve angular displacement detection without blind spots in the range of 0 to 360 degrees.

[0020] Furthermore, the AHE element can be prepared in the form of a wedge-shaped film, and directly output positive and negative voltage values ​​by sensing the difference in polarity of the magnetic field in the plane, so as to determine the direction of the magnetic field.

[0021] Furthermore, the AHE element can also be designed as two Hall bars placed at 90 degrees to each other in a plane, and output positive and negative voltages in different forms according to the different polarities of the induced magnetic field, so as to realize rapid magnetic field polarity determination.

[0022] A method for preparing a micro angular displacement magnetic probe chip for 360-degree blind spot detection comprises the following steps:

[0023] AMR thin film components are prepared on Si / SiO2 wafers using processes such as photolithography, etching, magnetron sputtering, planarization and heat treatment;

[0024] Depositing an insulating dielectric layer to electrically insulate the AMR element from the subsequent AHE element;

[0025] Prepare an AHE element having a wedge-shaped membrane structure or two Hall bars placed at 90 degrees to each other in a plane;

[0026] Depositing a protective layer to protect the remaining area on the chip except the PAD;

[0027] High-temperature heat treatment processes are used to enhance film density, reduce internal film defects, repair lattice damage, and improve wafer performance.

[0028] Furthermore, the preparation process of the AMR thin film element includes: coating photoresist, baking, aligning exposure, developing, and then using magnetron sputtering coating equipment to deposit Ta / NiFe / Ta, stripping the photoresist, completing the preparation of the main functional structure of the AMR element, and then completing the electrical connection between each group of magnetic resistance strips through photolithography and deposition of the interconnected conductive metal layer Cu.

[0029] Furthermore, the preparation process of the AHE element includes: after the planarization treatment, using a wedge film preparation process or photolithography, depositing two Hall bars placed at 90 degrees to each other to complete the preparation of the main functional structure of the AHE element, and finally completing the electrode PAD preparation of all elements by photolithography and deposition of a conductive metal layer Cu.

[0030] The application of a miniature angular displacement magnetic probe chip for 360-degree blind-spot detection places the sensor under a rotating magnetic field, calculates the rotation angle value based on the positive and cosine signals output by the double saturated Wheatstone bridge, and determines the magnetic field polarity in combination with the positive and negative voltage values ​​output by the AHE element, thereby achieving 360-degree blind-spot-free angular displacement detection.

[0031] Furthermore, when the calculated angle value calculated by the arc tangent solution of the AMR element is within a specific range, the angle interval in which the calculated angle value is actually located is determined according to the positive or negative value of one or more Hall bar output values ​​in the AHE element to determine the final angular displacement measurement result.

[0032] The beneficial effects achieved by the present invention are:

[0033] A miniature angular displacement magnetic probe chip with 360-degree blind spot detection can realize unique detection of any angle within the range of 0 to 360 degrees by integrating anisotropic magnetoresistive (AMR) elements and anomalous Hall effect (AHE) elements on one chip. The AMR element is responsible for high-precision measurement within the range of 0 to 180 degrees, while the AHE element is used to determine the polarity of the magnetic field, thereby solving the problem that traditional AMR sensors can only detect 0 to 180 degrees.

[0034] A miniature angular displacement magnetic probe chip with 360-degree blind-spot detection. Compared with the traditional solution that requires additional devices such as linear Hall sensors or TMR unipolar switches, the present invention integrates AMR and AHE elements on a single chip, which not only reduces the number of external components, but also reduces the complexity and volume of the system, making installation more convenient and using lower power consumption.

[0035] A micro angular displacement magnetic probe chip with 360-degree blind spot detection. The magnetic sensitive probe chip of the present invention has small hysteresis, high signal-to-noise ratio, simple film preparation process and low cost. Compared with GMR and TMR technology, it provides better stability and reliability while maintaining high resolution and operational stability.

[0036] A miniature angular displacement magnetic probe chip with 360-degree detection without blind spots. Due to the adoption of the magnetic signal detection principle, the magnetic sensitive chip has the characteristics of simple unit mechanical structure, vibration resistance, and noise resistance. It can work normally in various harsh environments and is suitable for multiple fields such as industry, green energy, aerospace, etc.

[0037] A miniature angular displacement magnetic probe chip with 360-degree detection without blind spots. This invention helps to promote the further miniaturization and integration of angular displacement sensing technology, meets the market demand for miniaturized, low-power, high-performance angular displacement sensors, and provides new possibilities for technological innovation in related industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] 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 the structures shown in these drawings without paying creative work.

[0039] Figure 1 This is a schematic diagram of the stacking structure of the magnetic angular displacement probe chip, in which 1 is the substrate-Si / SiO2, 2 is the AMR film layer, 3 is the insulating dielectric layer, 4 is the AHE film layer, and 5 is the passivation layer.

[0040] Figure 2 FIG. 1 is a schematic diagram of the layout structure of an AMR element including a double saturated Wheatstone bridge.

[0041] Figure 3 FIG. 4 is an output response curve of a schematic diagram of a layout structure of an AMR element including a double saturated Wheatstone bridge.

[0042] Figure 4 Schematic diagram of the structure of the AHE element based on the wedge-shaped membrane structure inducing magnetic field polarity in the embodiment.

[0043] Figure 5 1 is an output response curve of the schematic diagram of the AHE element structure based on the wedge-shaped membrane structure inducing magnetic field polarity in the embodiment.

[0044] Figure 6 1 is a schematic diagram of the layout structure of the AHE element based on the Hall bar induced magnetic field polarity placed at 90 degrees to each other in the horizontal plane and the output response curve in the embodiment.

[0045] Figure 7 It is a solution curve of the calculated angle value of the AMR element and the wedge-shaped film structure AHE element in Example 1 under the action of the magnetic steel rotating 0 to 360 degrees.

[0046] Figure 8 It is a solution curve of the calculated angle value of the AMR element and the planar film structure AHE element in Example 2 under the action of the magnetic steel rotating 0 to 360 degrees.

[0047] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0048] 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.

[0049] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0050] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if the meaning of "and / or" appearing in the full text is to include three parallel schemes, taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0051] The present invention provides a design and preparation method of a magnetic probe chip for realizing 0-360 degree angular displacement sensing without blind spots based on the anomalous Hall effect (AHE) and AMR elements. The AMR element is used to output sine and cosine signals to realize unique angular displacement detection of 0-180 degrees, and the AHE element is used as a means of magnetic field polarity discrimination to realize 0-360 degree angular displacement detection without blind spots of the sensor. The present invention integrates AMR and AHE elements on the magnetic sensitive probe chip at the same time, optimizes the layout structure design method, reduces the complexity of the chip preparation process and the device volume, and promotes the further miniaturization and integration of angular displacement sensing technology. Compared with traditional GMR and TMR angular displacement sensing technologies, the magnetic sensitive probe chip of the present invention has small hysteresis, high signal-to-noise ratio, simple and stable preparation process and low cost; compared with AMR angular displacement sensing technology that is additionally equipped with magnetic field polarity determination means such as Hall devices or TMR unipolar switching devices, the present invention realizes a unique angular displacement detection function of 0~360 degrees by integrating AMR and AHE elements on one chip, with a simpler structure, smaller size, higher integration and lower power consumption.

[0052] The technical solution of the present invention is as follows:

[0053] A 360-degree miniature angular displacement magnetic probe chip with no detection blind area, the specific structure of which includes a substrate, an AMR film, an insulating dielectric layer, an AHE film and a passivation layer from bottom to top, such as Figure 1 shown.

[0054] The substrate is a traditional silicon-based wafer, and several hundred nanometers of SiO2 are oxidized on Si to enhance the durability of the wafer, inhibit the wafer from warping and deformation during heating or cooling, and prevent dopants from penetrating into the silicon surface.

[0055] The AMR thin film structure is a seed layer / AMR magnetic functional layer / protective layer, wherein the seed layer is between the wafer and the AMR magnetic functional layer. Preferably, thin film materials such as Ta, Pt, or W are usually selected to improve the sensitivity of the AMR element; the AMR magnetic functional layer is used to realize angular displacement detection. Preferably, soft magnetic metal alloy materials such as NiFe or NiCo with low hysteresis, small saturation field, high magnetic permeability, and high Curie temperature are usually selected; the protective layer is used to protect the AMR magnetic functional layer from being oxidized and polluted by the external environment. Preferably, thin film materials such as Ta, Pt, or MgO are usually selected.

[0056] The insulating dielectric layer is used for electrical insulation between different metal layers, and preferably, insulating materials such as SiO2 or Si3N4 are usually selected.

[0057] The AHE thin film structure is a buffer layer / active layer / covering layer. The buffer layer is used to improve the AHE performance. Preferably, heavy metal materials such as Ta, Pt or W are usually selected. The active layer is used to generate AHE to realize the magnetic field polarity discrimination function. Preferably, thin film materials such as CoFeB, Co / Pt or CoFe / Pt are usually selected. The covering layer usually uses thin film materials such as Pt, MgO or SiO2 to protect and optimize the AHE performance.

[0058] The passivation layer is used to protect the magnetic thin film element during electrical testing, packaging and use. Preferably, an insulating material such as SiO2 or Si3N4 is usually selected.

[0059] The design method of the above-mentioned micro angular displacement magnetic probe chip for 360-degree blind spot detection is as follows:

[0060] The AMR effect refers to the fact that the resistance of ferromagnetic materials such as Permalloy changes with the angle between the material's own magnetic moment orientation and the direction of current flow. Therefore, by applying a rotating external saturation magnetic field to the AMR element, the resistance change of the AMR element can be sensitively controlled. The resistance expression is R=R ⊥ +(R ∥ -R ⊥ )cos 2 θ, where R ⊥ is the resistance of the AMR element when the magnetic moment is oriented perpendicular to the direction of current flow, R ∥ is the resistance when the magnetic moment orientation of the AMR element is parallel to the direction of current flow, and θ is the angle between the magnetic moment orientation of the AMR element and the direction of current flow. Based on this changing relationship between the AMR element R and θ, an AMR element output sine and cosine curves containing a double saturated Wheatstone bridge can be designed to achieve unique angular displacement detection of 0 to 180 degrees, such as Figure 2 , 3 As shown. The voltage output expressions of the double saturated Wheatstone bridge are V1=V Ssin2θ×(R ∥ -R ⊥ ) / 2R0, V2=V S cos2θ×(R ∥ -R ⊥ ) / 2R0, where V S is the supply voltage, and R0 is the resistance of the AMR element in the absence of an external magnetic field. The voltage signals output by the two bridges are reversely switched to calculate the angle of rotation of the external saturation magnetic field, that is, the detected rotation angle α=0.5arctan(V1 / V2). The AHE effect refers to the abnormal Hall voltage value in ferromagnetic metals being proportional to the magnetization intensity of the material itself, and the Hall resistance can be expressed as R xy =R OH B Z +R AH M Z , where R OH , R AH They are the normal Hall coefficient and the abnormal Hall coefficient (R AH ≥10R OH ), B Z 、M Z They are the magnetic induction intensity in the Z-axis direction outside the plane and the magnetization intensity of the magnetic material. The AHE element made using the AHE principle can output voltage values ​​of different polarities according to the different directions of the induced magnetic field, thereby playing the role of magnetic field polarity determination.

[0061] The double saturated Wheatstone bridge is usually designed as two Wheatstone bridges placed at 45 degrees, such as Figure 2 As shown, each Wheatstone bridge is usually composed of four groups of magnetoresistive strip arrays placed at 90 degrees to each other to improve parameters such as sensitivity, signal-to-noise ratio, and temperature stability.

[0062] The AHE element is usually designed as a Hall bar in the shape of a cross to distinguish the magnetic field polarity to achieve 0-360 degree angular displacement detection without blind spots, such as Figure 4 , 5 , as shown in Figure 6.

[0063] In order to achieve the application purpose of determining the polarity of the magnetic field, on the one hand, the AHE element can be prepared in the form of a wedge-shaped film, and directly output positive and negative voltage values ​​by sensing the different polarities of the magnetic field in the plane, such as Figure 4 , 5As shown in the figure, within the out-of-plane saturation magnetic field range, the anomalous Hall output curve of the AHE element with in-plane magnetic anisotropy is approximately a straight line passing through the zero point, and its value changes linearly with the change of the external magnetic field. The hysteresis is close to 0. Therefore, the direction of the magnetic field can be determined according to the positive and negative output value of the AHE element. On the other hand, the AHE element can also be designed as two Hall bars placed at 90 degrees to each other in the plane, as shown in the figure. Figure 6 As shown, a certain current I is applied 写 When the AHE element with perpendicular magnetic anisotropy can output positive and negative voltages according to the different polarities of the induced magnetic field due to the spin Hall effect and spin-orbit torque, the speed of this process can reach sub-nanosecond level, and when reading the output voltage, the I 写 Reduced to a current of only tens of microamperes I 读 In order to reduce the power consumption of the device, because the AHE element requires at least several Gs of external magnetic field strength to achieve this magnetic field polarity discrimination output mode, it is necessary to design two Hall bars placed at 90 degrees to compensate each other. Among them, the positive and negative output values ​​of Hall bar B can be used to determine whether the rotation angle value is 45~135 degrees or 225~315 degrees, and the positive and negative output values ​​of Hall bar A can be used to determine the remaining angle range. Compared with the current semiconductor Hall sensor, the magnetic field sensor based on the AHE principle has lower resistivity, wider response frequency, better thermal stability, higher sensitivity, and has the application advantage of simple preparation process. The magnetic sensitive probe chip stacking structure in this design and preparation method is simple, highly integrated, small in size, simple in preparation process, and low in power consumption, which is conducive to the further miniaturization and integration of angular displacement sensing technology.

[0064] In summary, the magnetic angular displacement sensor chip designed by the present invention integrates the AHE element with the magnetic field polarity determination function and the AMR magnetic probe chip with the 180-degree unique angular displacement detection function on one chip. It is no longer necessary to use additional linear Hall sensors or Hall switches or TMR unipolar switches and other sensor types to achieve 360-degree angular displacement detection without blind spots. The structure is simpler, the installation method is more portable, and the power consumption is lower, which promotes the miniaturization and integrated application of angular displacement sensing technology. In addition, compared with the currently traditionally used GMR, TMR and other angular displacement sensing technologies, the magnetic probe chip of the present invention also has the application advantages of small hysteresis, high signal-to-noise ratio, simple thin film preparation process, low cost, and high reliability.

[0065] A magnetically sensitive angular displacement probe chip for 360-degree detection without blind spots is prepared on a wafer by using processes such as photolithography, etching, magnetron sputtering, flattening and heat treatment.

[0066] Example 1

[0067] Step 1: Si / SiO2 wafer is selected as the substrate, and photoresist coating, baking, alignment exposure, development and other process operations are carried out on it to photolithograph the AMR thin film element pattern with 180-degree unique angular displacement detection function, and then Ta (5nm) / NiFe (22nm) / Ta (3nm) are deposited in sequence using magnetron sputtering coating equipment, and the photoresist is stripped off to complete the preparation of the main functional structure of the AMR element. Finally, the electrical connection between each group of magnetic resistance strips is completed through photolithography and deposition of the interconnected conductive metal layer Cu, such as Figure 2 shown.

[0068] Step 2: Further, a 0.6 μm thick SiO2 insulating dielectric layer is deposited on the wafer using a coating device to perform electrical insulation between the AMR element and the subsequent AHE element.

[0069] Step 3: After the planarization treatment, the wedge-shaped film preparation process is used to continue photolithography and deposition of Hall bars with a wedge-shaped film structure on the wafer, such as Figure 4 As shown, the thin film structure is Pt(5nm) / [CoFe(0.4nm) / Pt(1.5nm)]3 / Fe(0.5nm) / Pt(1.5nm). After the main functional structure of the AHE element is prepared, it is flattened again. The electrode PAD preparation of all elements is completed through photolithography and deposition of the conductive metal layer Cu.

[0070] Step 4: Further, a 0.8μm thick SiO2 protective layer is photolithographically deposited on the wafer to cover and protect the remaining areas on the chip except for the PAD. After that, a high-temperature heat treatment process is used to enhance the density of the film, reduce internal defects of the film, repair lattice damage, and improve wafer performance.

[0071] Step 5: When testing the angular displacement detection function, place the sensor under a magnet (10mm in diameter, 1mm in thickness) that rotates from 0 to 360 degrees. The relationship curve between the actual angle value of the magnet rotation and the calculated angle value can be calculated by inverse tangent solution based on the positive and cosine signals output by the double saturated Wheatstone bridge (first solution). Further, the positive and negative output values ​​of the double saturated Wheatstone bridge are processed and analyzed in quadrants to achieve 180-degree unique angular displacement detection of the AMR element (second solution). The specific processing and analysis process is as follows: the initial angle value obtained by inverse tangent calculation is α=0.5arctan(V1 / V2) (first solution). Further When V1 and V2 output positive at the same time, the angle value of the second solution is α+0°, when V1 output is positive and V2 output is negative, the angle value of the second solution is α+90°, when V1 and V2 output are negative at the same time, the angle value of the second solution is α+90°, and when V1 output is negative and V2 output is positive, the angle value of the second solution is α+180°; further, the magnetic field polarity is determined according to the positive and negative voltage values ​​output by the AHE element to determine whether the solution angle value is within the range of 0 to 180 degrees or within the range of 180 to 360 degrees, thereby realizing 360-degree angular displacement detection without blind spots (third solution). The angle solution process is as follows: Figure 7 shown.

[0072] Example 2

[0073] Step 1: Select Si / SiO2 wafer as substrate, photolithography, deposit AMR film, the structure order is Ta(5nm) / NiFe(22nm) / Ta(3nm), strip the photoresist, and complete the AMR element preparation by photolithography and deposition of interconnection conductive metal layer Cu, such as Figure 2 shown.

[0074] Step 2: Deposit a 0.6 μm thick SiO2 insulating dielectric layer on the wafer to provide electrical insulation between the AMR element and the subsequent AHE element.

[0075] Step 3: After the planarization treatment, two Hall bars are placed at 90 degrees to each other on the wafer by photolithography and deposition. The structure is Ta(5nm) / CoFeB(1.4nm) / MgO(2), completing the preparation of the main functional structure of the AHE element. Figure 6 As shown, finally, the PAD preparation of all components is completed through photolithography and deposition of a conductive metal layer Cu.

[0076] Step 4: Photolithography and deposition of a 0.8μm thick SiO2 protective layer on the wafer to cover and protect the remaining areas on the chip except the PAD. Then, a high-temperature heat treatment process is used to enhance the density of the film, reduce internal defects in the film, repair lattice damage, and improve wafer performance.

[0077] Step 5: When testing the angular displacement detection function, place the sensor under a magnet (10mm in diameter, 1mm in thickness) that rotates from 0 to 360 degrees. The rotation angle of the magnet can be calculated by the inverse tangent based on the positive and cosine signals output by the double saturated Wheatstone bridge to achieve 180-degree unique angular displacement detection. The positive and negative voltage values ​​output by the two sets of Hall bars in the AHE element can be used to identify the polarity of the magnetic field to determine the angle range in which the calculated angle value is located, thereby achieving 360-degree angular displacement detection without blind spots. The angle calculation process is as follows: Figure 8 As shown, the specific processing and analysis process is: when the calculated angle value calculated by the inverse tangent solution of the AMR element is in the range of 0~45 degrees, the calculated angle value is actually determined to be 0~45 degrees or 180~225 degrees according to the positive and negative output value of Hall bar A; when the calculated angle value calculated by the inverse tangent solution of the AMR element is in the range of 45~135 degrees, the calculated angle value is actually determined to be 45~135 degrees or 225~315 degrees according to the positive and negative output value of Hallbar B; when the calculated angle value calculated by the inverse tangent solution of the AMR element is in the range of 135~180 degrees, the calculated angle value is actually determined to be 135~180 degrees or 315~360 degrees according to the positive and negative output value of Hall bar A.

[0078] It can be seen from the above embodiments that the magnetic angular displacement sensor chip design method of the present invention can realize a 360-degree angular displacement detection function without blind spots through appropriate structural design and thin film preparation process. The chip has the advantages of small size, high precision, high integration, low power consumption, low cost, good stability, etc. It can overcome the shortcomings of angular displacement sensors in the current market and meet the application requirements of miniaturization, wide range, high precision and high reliability of angular displacement detection.

[0079] The above descriptions are only optional embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A 360-degree blind-zone-free micro-angular displacement magnetic probe chip, characterized in that: The chip includes, from bottom to top: Substrate (1), the substrate is a conventional silicon-based wafer, with several hundred nanometers of SiO2 oxidized on the Si; AMR film layer (2), the AMR film structure is a seed layer / AMR magnetic functional layer / protective layer, wherein the AMR magnetic functional layer is made of NiFe or NiCo with low hysteresis, small saturation field, high magnetic permeability and high Curie temperature; An insulating dielectric layer (3) for electrical insulation between different metal layers; An AHE thin film layer (4), wherein the AHE thin film structure is a buffer layer / active layer / covering layer, and the active layer is used to generate an anomalous Hall effect to achieve a magnetic field polarity discrimination function; The passivation layer (5) is used to protect the magnetic thin film element from being affected by the external environment during electrical testing, packaging and use.

2. The micro angular displacement magnetic probe chip according to claim 1, characterized in that: The AMR film layer (2) adopts a double saturated Wheatstone bridge structure, each Wheatstone bridge is composed of four groups of magnetoresistive strip arrays placed at 90 degrees to each other, so as to improve sensitivity, signal-to-noise ratio, and temperature stability parameter indicators.

3. The micro angular displacement magnetic probe chip according to claim 1, characterized in that: The AHE thin film layer (4) is designed to be a Hall bar in the shape of a cross, and is used to identify the polarity of the magnetic field, so as to achieve angular displacement detection without blind spots in the range of 0 to 360 degrees.

4. The micro angular displacement magnetic probe chip according to claim 3, characterized in that: The AHE element is prepared in the form of a wedge-shaped film, and directly outputs positive and negative voltage values ​​by sensing the difference in polarity of the magnetic field in the plane, which is used to determine the direction of the magnetic field.

5. The micro angular displacement magnetic probe chip according to claim 3, characterized in that: The AHE element is designed as two Hall bars placed at 90 degrees to each other in a plane, and outputs positive and negative voltages in different forms according to the different polarities of the induced magnetic field, so as to realize rapid magnetic field polarity determination.

6. A method for preparing a 360-degree blind-zone-free micro angular displacement magnetic probe chip according to any one of claims 1 to 5, characterized in that: The following steps are involved: AMR thin film components are fabricated on Si / SiO2 wafers using photolithography, etching, magnetron sputtering, planarization, and heat treatment processes; Depositing an insulating dielectric layer to electrically insulate the AMR element from subsequent AHE elements; Prepare an AHE element having a wedge-shaped membrane structure or two Hall bars placed at 90 degrees to each other in a plane; Depositing a protective layer to protect the remaining area on the chip except the PAD; High-temperature heat treatment processes are used to enhance film density, reduce internal film defects, repair lattice damage, and improve wafer performance.

7. The preparation method according to claim 6, characterized in that: The preparation process of the AMR thin film element includes: coating photoresist, baking, aligning exposure, developing, then using magnetron sputtering coating equipment to deposit Ta / NiFe / Ta, stripping the photoresist, completing the preparation of the main functional structure of the AMR element, and then completing the electrical connection between each group of magnetic resistance strips through photolithography and deposition of the interconnected conductive metal layer Cu.

8. The preparation method according to claim 6, characterized in that: The preparation process of the AHE element includes: after planarization, using a wedge film preparation process or photolithography and depositing two Hall bars placed at 90 degrees to each other to complete the preparation of the main functional structure of the AHE element, and finally completing the electrode PAD preparation of all elements by photolithography and deposition of a conductive metal layer Cu.

9. An application of the 360-degree blind-zone-free micro angular displacement magnetic probe chip as claimed in any one of claims 1 to 5, characterized in that: The sensor is placed under a rotating magnetic field, and the rotation angle value is calculated based on the positive and cosine signals output by the double saturated Wheatstone bridge. The polarity of the magnetic field is determined by combining the positive and negative voltage values ​​output by the AHE element, thereby achieving 360-degree angular displacement detection without blind spots.

10. The use according to claim 9, characterized in that: When the calculated angle value calculated by the arc tangent solution of the AMR element is within a specific range, the angle interval in which the calculated angle value actually lies is determined according to the positive or negative value of one or more Hall bar output values ​​in the AHE element to determine the final angular displacement measurement result.

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