Magnetic sensor chip and method for manufacturing the same, and magnetic encoder

Abstract

The application provides a magnetic sensor chip and a preparation method thereof and a magnetic encoder. The magnetic sensor chip comprises a substrate, a magnetoresistance element group arranged on the substrate and an electrode connected with the magnetoresistance element group. The magnetoresistance element group is arranged as eight groups, and the eight groups of magnetoresistance element groups are uniformly distributed along the same center. Each group of magnetoresistance element groups comprises two magnetoresistance elements, each of which comprises four magnetoresistance strips which are concentric with the magnetoresistance element group and are uniformly distributed in a fan shape. The central angle of the magnetoresistance strips of one magnetoresistance element in each group of magnetoresistance element groups and the magnetoresistance strips at the corresponding position of the other magnetoresistance element is 15°. The central angle of the magnetoresistance strips in one group of magnetoresistance element groups and the magnetoresistance strips at the corresponding position of the other group of magnetoresistance element groups adjacent to the one group of magnetoresistance element groups is 30°. Through the arrangement mode of the magnetoresistance element group and the magnetoresistance strips constituting the magnetoresistance element, the third harmonic in the chip output signal can be effectively eliminated, the output signal is closer to the complete sine wave and cosine wave, and the detection resolution of the rotation angle is improved.

Description

Technical Field

[0001] This invention relates to the field of rotation angle measurement technology, and in particular to a magnetic sensor chip, its fabrication method, and a magnetic encoder. Background Technology

[0002] A magnetic encoder is a device that uses magnetic field detection to measure and position rotation angles. It mainly consists of a magnetic code disk, a magnetic sensor, a mechanical support structure, and a signal processing module. The resolution of a magnetic encoder is affected by many factors, such as the relative positions of the magnetic code disk and the magnetic sensor chip, the mechanical structure design of the encoder, and the design of the signal processing module. For the magnetic sensor chip, its resolution determines whether the waveform output by the corresponding magnetic encoder is a complete sine wave. The closer the two-phase original waveform signals output by the magnetic encoder are to sine and cosine waves, the higher the accuracy of the signal-to-angle conversion, and the better it is for the subsequent subdivision circuitry in the signal processing circuit.

[0003] Currently, the anisotropic magnetoresistive materials used to fabricate magnetoresistive elements in magnetic sensor chips exhibit a saturation phenomenon in the change of resistivity in a magnetic field. This means that the fabricated magnetoresistive elements will output high-order harmonic components, causing interference and thus affecting the overall resolution of the magnetic sensor chip. Summary of the Invention

[0004] The purpose of this invention is to solve the technical problem that magnetoresistive elements in the prior art output high-order harmonic components, thereby affecting the overall resolution of magnetic sensor chips.

[0005] To solve the above-mentioned technical problems, the present invention provides a magnetic sensor chip, including a substrate, a group of magnetoresistive elements disposed on the substrate, and electrodes connected to the group of magnetoresistive elements. The chip is characterized in that: the group of magnetoresistive elements is configured as eight groups, which are uniformly arranged along the same center; each group of magnetoresistive elements includes two magnetoresistive elements, and each magnetoresistive element includes four magnetoresistive strips concentric with the group and evenly distributed in a fan shape; the central angle between the magnetoresistive strip of one magnetoresistive element and the corresponding magnetoresistive strip of another magnetoresistive element in each group is 15°; the central angle between the magnetoresistive strip of one group and the corresponding magnetoresistive strip of an adjacent group is 30°.

[0006] Optionally, the magnetoresistive strip is made of anisotropic magnetoresistive thin film material.

[0007] Optionally, the anisotropic magnetoresistive thin film material is a Ni80Fe20 alloy.

[0008] Optionally, the magnetic reluctance strip is rectangular.

[0009] Optionally, the magnetic reluctance strip has a length of 200 μm and a width of 8 μm.

[0010] This application also provides a method for fabricating a magnetic sensor chip, which includes the following steps:

[0011] S01. A multilayer film structure of anisotropic magnetoresistive material is deposited using a silicon wafer as a substrate by magnetron sputtering.

[0012] S02. A silicon wafer substrate with a multilayer film structure is etched into magnetoresistive strips using microfabrication technology, and multiple magnetoresistive strips are arranged to form a magnetoresistive element.

[0013] S03. Sputtering and growing a metal electrode layer on the magnetoresistive element;

[0014] S04. Electrode patterns are fabricated using an overlay process and connected to various magnetoresistive elements.

[0015] Optionally, in step S01, the multilayer film structure of the anisotropic magnetoresistive material is a Ta / NiFe / Ta film, wherein the thickness of the Ta layer is 3-10 nm, the thickness of the NiFe layer is 20-50 nm, the base vacuum of the equipment during sputtering is better than 3.0 × 10-7 Torr, and an orientation magnetic field needs to be applied to both sides of the silicon substrate.

[0016] Optionally, in step S03, the grown metal electrode layer film is a metal material with excellent conductivity such as Au, Ag, Cu, Cr, Al, Pt, etc., with a thickness of 50-300 nm and a base vacuum better than 3.0 × 10-7 Torr during sputtering.

[0017] This application also provides a magnetic encoder, which includes the magnetic sensor chip, magnetic code disk, mechanical support structure and signal processing module described in any of the above claims.

[0018] Optionally, the magnetic code disk is a single-pole magnet or a multi-pole circular magnet, and the magnetic code disk is concentrically arranged with the magnetic sensor chip.

[0019] As can be seen from the above technical solution, the beneficial effects of the present invention are as follows:

[0020] A magnetic sensor chip, its fabrication method, and a magnetic encoder are disclosed. The magnetic sensor chip includes a substrate, a group of magnetoresistive elements disposed on the substrate, and electrodes connected to the magnetoresistive element groups. The magnetoresistive element groups are configured in eight groups, uniformly arranged along the same center. Each group includes two magnetoresistive elements, and each magnetoresistive element includes four magnetoresistive strips concentric with the group and evenly distributed in a fan shape. The central angle between the magnetoresistive strip of one magnetoresistive element and the corresponding magnetoresistive strip of another magnetoresistive element in each group is 15°; the central angle between the magnetoresistive strip of one group and the corresponding magnetoresistive strip of an adjacent group is 30°. Through the above arrangement of the magnetoresistive element groups and the magnetoresistive strips constituting the magnetoresistive elements, the third harmonic in the chip's output signal can be effectively eliminated, making the output signal closer to a complete sine and cosine wave, thereby improving the detection resolution of the rotation angle. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of an embodiment of the magnetic sensor chip provided in this application.

[0022] Figure 2 This is a detailed diagram of the magnetoresistive element in one embodiment of the magnetic sensor chip provided in this application.

[0023] The annotations in the attached figures are explained as follows:

[0024] 10. Magnetoresistive element group; 11. Magnetoresistive element; 111. Magnetoresistive strip; 20. Electrode. Detailed Implementation

[0025] Typical embodiments embodying the features and advantages of the present invention will be described in detail in the following description. It should be understood that the present invention can have various variations in different embodiments without departing from the scope of the present invention, and the descriptions and illustrations herein are for illustrative purposes only and not intended to limit the present invention.

[0026] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0027] To further illustrate the principles and structure of the present invention, preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0028] Please see Figure 1 This application provides a magnetic sensor chip that is beneficial for third harmonic elimination when applied to a magnetic encoder. The magnetic sensor chip includes a substrate (not shown in the figure), a magnetoresistive element group 10 and an electrode 20 disposed on the substrate.

[0029] like Figure 1 As shown, the magnetoresistive element group 10 is configured in eight groups, which are evenly arranged along the same center and at the same distance from the center. The length direction of the eight groups of magnetoresistive element groups 10 is consistent with the direction of radiation outward from the center. Each group of magnetoresistive element groups 10 includes two magnetoresistive elements 11, and the magnetic sensor chip has a total of 16 magnetoresistive elements 11. Please refer to [link / reference]. Figure 2 Specifically, the 16 magnetoresistive elements 11 are named R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, R12, R13, R14, R15, and R16 in a counterclockwise direction. Among them, R1 and R16, R2 and R3, R4 and R5, R6 and R7, R8 and R9, R10 and R11, R12 and R13, and R14 and R15 respectively form eight groups of the magnetoresistive elements 10.

[0030] Each magnetoresistive element 11 includes four magnetoresistive strips 111 concentric with and evenly distributed in a fan shape with the magnetoresistive element group 10. The central angle between the magnetoresistive strip 111 of one magnetoresistive element 11 and the corresponding magnetoresistive strip 111 of another magnetoresistive element 11 in each magnetoresistive element group 10 is 15°, and the central angle between the magnetoresistive strip 111 of one magnetoresistive element group 10 and the corresponding magnetoresistive strip 111 of another adjacent magnetoresistive element group 10 is 30°. Specifically, taking R1, R2, and R3 of the magnetoresistive element 11 as examples, such as... Figure 2 As shown, R1 and R2 are located in two adjacent magnetoresistive element groups 10, and R2 and R3 are located in the same magnetoresistive element group 10. The four magnetoresistive strips 111 in R1 are named R1-1, R1-2, R1-3, and R1-4 in a counterclockwise direction. The four magnetoresistive strips 111 in R2 are named R2-1, R2-2, R2-3, and R2-4 in a counterclockwise direction. The four magnetoresistive strips 111 in R3 are named R1-1, R1-2, R1-3, and R1-4 in a counterclockwise direction. The magnetoresistive elements are sequentially named R3-1, R3-2, R3-3, and R3-4 in a counter-clockwise direction. R1-1 and R2-1 are magnetoresistive strips 111 at corresponding positions in two adjacent magnetoresistive element groups 10, with a central angle of 30° between them. R2-1 and R3-1 are magnetoresistive strips 111 at corresponding positions between two magnetoresistive elements 11 in the same magnetoresistive element group 10, with a central angle of 15° between them. Through the above arrangement of the magnetoresistive element groups 10 and the magnetoresistive strips 111 constituting the magnetoresistive elements 11, the third harmonic in the chip output signal can be effectively eliminated, making the output signal closer to a complete sine and cosine wave, thereby improving the detection resolution of the rotation angle.

[0031] In this embodiment, the magnetoresistive strip 111 is rectangular, with a length of 200 μm and a width of 8 μm. The magnetoresistive strip 111 is made of anisotropic magnetoresistive film material, specifically a Ni80Fe20 alloy. It is understood that the length and width of the magnetoresistive strip 111 can be changed, as long as the magnetoresistive strip 111 satisfies the concentricity and the aforementioned angular arrangement. The material of the magnetoresistive strip 111 can also be a multilayer film structure of other heavy metals and anisotropic magnetoresistive materials such as NiCo, or an oxide intercalation layer can be added to Ta / NiFe / Ta. By adopting a rectangular or other strip-shaped structure for the magnetoresistive strip 111, compared to the previous arc-shaped structure, the lines are simpler, the area is larger, the requirements for process difficulty are lower, and process compatibility can be effectively improved.

[0032] The electrodes 20 are disposed on the substrate and are used for power supply and signal output. In this embodiment, a plurality of the electrodes 20 are arranged around the magnetoresistive element group 10.

[0033] This application also provides a magnetic encoder, which includes the aforementioned magnetic sensor chip, magnetic code disk, mechanical support structure, and signal processing module. The mechanical support structure provides mounting support for the components within the magnetic encoder, and the signal processing module processes the signal output by the magnetic sensor chip. In this embodiment, the magnetic code disk can be a single-pole magnet or a multi-pole circular magnet; during assembly, it must be ensured that the magnet is concentric with the magnetic sensor chip. In use, when the magnetic code disk rotates through a certain angle, i.e., the periodic magnetic field changes by a certain angle, the magnetoresistive element 11, made of anisotropic magnetoresistive material, changes its magnetoresistive resistance due to the different spatial arrangements. The output electrode can extract sine and cosine signals, and angle extraction and measurement can be achieved using the arctangent formula.

[0034] Specifically, when the magnetic code disk rotates by an angle of δ, the magnetic sensor chip corresponding to the magnetic code disk has a frequency doubling characteristic, that is, the angle of the output signal response is 2δ, written as θ = 2δ. Similarly, when the angle of the output signal response of R1 is θ = 2δ, the angle of the output signal response of R2 is... Let the zero-field resistance of R1, R2, R5, and R6 in the magnetoresistive element 11 be R, and the applied power supply voltage be V. Then the resistance values ​​of R1, R2, R5, and R6 can be written in Fourier expansion mode:

[0035]

[0036]

[0037]

[0038]

[0039] The magnitude of the output signal between R1 and R2 and R5 and R6 is:

[0040]

[0041]

[0042] When n is odd, that is, when n = 2m - 1, we have:

[0043] cosn(θ+π)=-cosnθ

[0044]

[0045]

[0046]

[0047] When n is even, that is, when n = 2m, we have:

[0048] cosn(θ+π)=cosnθ

[0049]

[0050]

[0051] The above formula can then be written as:

[0052]

[0053]

[0054] It can be seen that when n is 3 or a multiple of 3, the effective value of the output harmonic signal is 0.

[0055] Therefore, it can be considered that the magnetic sensor chip is effective in eliminating the third harmonic signal.

[0056] This application also provides a method for fabricating a magnetic sensor chip, the magnetic sensor chip being obtained based on the fabrication method, the fabrication method comprising the following steps:

[0057] S01. A multilayer film structure of anisotropic magnetoresistive material is deposited using a silicon wafer as a substrate by magnetron sputtering.

[0058] Specifically, the silicon wafer is polished on one side, with a 300nm thick SiO2 insulating layer deposited on its surface. The anisotropic magnetoresistive material is a multilayer Ta / NiFe / Ta film, where the Ta layer is 3-10nm thick and the NiFe layer is 20-50nm thick. The base vacuum of the equipment during sputtering is better than 3.0×10⁻⁷ Torr, and an orientation magnetic field needs to be applied to both sides of the silicon substrate. Understandably, the Ta / NiFe / Ta film can be replaced with other multilayer structures of heavy metals and anisotropic magnetoresistive materials such as NiCo, or oxide intercalations can be added to the Ta / NiFe / Ta.

[0059] S02. A silicon wafer substrate with a multilayer film structure is etched into magnetoresistive strips using microfabrication technology, and multiple magnetoresistive strips are arranged to form a magnetoresistive element.

[0060] Specifically, the magnetoresistive strips obtained by photolithography and other microfabrication processes are 200 μm long and 8 μm wide, and the four magnetoresistive strips are arranged in a fan shape to form a magnetoresistive element.

[0061] S03. Sputtering and growing a metal electrode layer on the magnetoresistive element;

[0062] Specifically, the metal electrode layer film is grown from metal materials with excellent conductivity such as Au, Ag, Cu, Cr, Al, and Pt, with a thickness of 50-300 nm, and the background vacuum during sputtering is better than 3.0 × 10-7 Torr.

[0063] S04. Electrode patterns are fabricated using an overlay process and connected to various magnetoresistive elements.

[0064] This application provides a magnetic sensor chip, its fabrication method, and a magnetic encoder. The magnetic sensor chip includes a substrate, a magnetoresistive element group 10 disposed on the substrate, and electrodes 20 connected to the magnetoresistive element group 10. The magnetoresistive element group 10 is configured as eight groups, uniformly arranged along the same center. Each group of magnetoresistive element groups 10 includes two magnetoresistive elements 11, and each magnetoresistive element 11 includes four magnetoresistive strips 111 concentric with the magnetoresistive element group 10 and evenly distributed in a fan shape. The central angle between the magnetoresistive strip 111 of one magnetoresistive element group 10 and the corresponding magnetoresistive strip 111 of another magnetoresistive element group 10 is 15°. The central angle between the magnetoresistive strip 111 of one group of magnetoresistive element groups 10 and the corresponding magnetoresistive strip 111 of another adjacent group of magnetoresistive element groups 10 is 30°. By arranging the magnetoresistive element group 10 and the magnetoresistive strip 111 constituting the magnetoresistive element 11, the third harmonic in the chip output signal can be effectively eliminated, making the output signal closer to a complete sine wave and cosine wave, thereby improving the detection resolution of the rotation angle.

[0065] Although the invention has been described with reference to several typical embodiments, it should be understood that the terminology used is illustrative and exemplary, and not restrictive. Since the invention can be embodied in many forms without departing from the spirit or essence of the invention, it should be understood that the above embodiments are not limited to any of the foregoing details, but should be interpreted broadly within the spirit and scope defined by the appended claims. Therefore, all variations and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.

Claims

1. A magnetic sensor chip comprising a substrate, a set of magnetoresistive elements provided on the substrate, and electrodes connected to the set of magnetoresistive elements, characterized in that: The magnetic resistance element groups are arranged as eight groups, and the eight groups of the magnetic resistance element groups are evenly arranged along the same center; each of the magnetic resistance element groups comprises two magnetic resistance elements, each of the magnetic resistance elements comprises four magnetic resistance strips which are evenly arranged in a fan shape and concentric with the magnetic resistance element group; the central angle of the magnetic resistance strip in one magnetic resistance element and the corresponding magnetic resistance strip in the other magnetic resistance element in each of the magnetic resistance element groups is 15°; the central angle of the magnetic resistance strip in one magnetic resistance element group and the corresponding magnetic resistance strip in the other magnetic resistance element group is 30°; wherein: The magnetic resistance strips are prepared by using an anisotropic magnetoresistance film material; The magnetic resistance strips adopt a rectangular structure.

2. The magnetic sensor chip according to claim 1, characterized in that The anisotropic magnetoresistance thin film material is Ni 80 Fe 20 alloy.

3. The magnetic sensor chip according to claim 1, characterized in that The length of the magnetic resistance strip is 200 μm, and the width is 8 μm.

4. A method of producing a magnetic sensor chip, the magnetic sensor chip according to claim 1 being obtained on the basis of the method of production, characterized in that, The method comprises the following steps: S01, using a silicon wafer as a substrate, depositing a multi-layer film structure of anisotropic magnetoresistance material by using a magnetron sputtering method; S02, etching the silicon wafer substrate with the deposited multi-layer film structure into magnetic resistance strips by using a micro-processing process, and arranging a plurality of the magnetic resistance strips to form a magnetic resistance element; S03, sputtering and growing a metal electrode layer film on the magnetic resistance element; S04, processing an electrode pattern by using a mask etching process, and connecting the magnetic resistance elements.

5. The production method according to claim 4, characterized by, In the step S01, the multilayer film structure of the anisotropic magnetoresistance material is Ta / NiFe / Ta film, wherein the thickness of the Ta layer is 3-10 nm, the thickness of the NiFe layer is 20-50 nm, the base vacuum of the equipment in the sputtering process is better than 3.0×10 -7 Torr, and an orientation magnetic field needs to be applied to both sides of the silicon wafer substrate.

6. The production method according to claim 4, characterized by, In the step S03, the metal electrode layer film is Au, Ag, Cu, Cr, Al or Pt, and the thickness is 50-300 nm. The base vacuum during sputtering is better than 3.0 x 10 -7 Torr.

7. A magnetic encoder characterized by, The magnetic sensor chip, the magnetic code disc, the mechanical support structure and the signal processing module are as claimed in any one of claims 1 to 3.

8. The magnetic encoder of claim 7, wherein, The magnetic code disc is a single pair of pole magnet or a multi-pair pole circular magnet, and the magnetic code disc is arranged concentrically with the magnetic sensor chip.

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