Manufacturing method of AMR sensor

Abstract

The invention discloses a manufacturing method of an AMR sensor. The method comprises the following steps: 1) spin-coating photoresist on the surface of a silicon wafer; 2) carrying out first photoetching on the glued silicon wafer to obtain a silicon wafer engraved with a magnetic resistance strip pattern and a shielding strip pattern; 3) performing magnetron sputtering on the silicon wafer engraved with the magnetic resistance strip and shielding strip patterns, and performing photoresist removal on the silicon wafer after magnetron sputtering to obtain a silicon wafer with a magnetron sputtering magnetic resistance layer; 4) annealing the silicon wafer with the magnetron sputtering magnetic resistance layer, and spin-coating photoresist on the annealed silicon wafer to obtain a silicon wafer coated with the photoresist for the second time; 5) performing secondary photoetching on the silicon wafer subjected to secondary gluing to obtain a silicon wafer engraved with an external electrode pattern; 6) performing thermal evaporation coating on the silicon wafer engraved with the external electrode pattern, and performing photoresist removal on the silicon wafer after thermal evaporation coating to obtain a silicon wafer with an AMR electrode layer; and 7) packaging the silicon wafer with the AMR electrode layer to obtain the AMR sensor. According to the invention, the manufacturing process of the traditional AMR sensor is simplified. The size of the AMR sensor is reduced.

Description

Technical Field

[0001] The present invention relates to the field of integrated circuit manufacturing, and in particular to a method for manufacturing an AMR sensor. Background Art

[0002] Photolithography is a process technology that uses optical-chemical reaction principles and chemical and physical etching methods in integrated circuit manufacturing to transfer circuit patterns to the surface of a single crystal or a dielectric layer to form an effective graphic window or functional pattern. With the development of semiconductor technology, the size limit of patterns transferred by photolithography has been reduced by 2-3 orders of magnitude (from millimeter level to submicron level). It has developed from conventional optical technology to new technologies such as electron beam, X-ray, micro-ion beam, laser, etc.; the wavelength used has been expanded from 4000 angstroms to 0.1 angstroms. Photolithography has become a precise micro-machining technology.

[0003] In traditional processes, the production of AMR sensors requires photolithography to form predefined patterns. However, due to the low development accuracy in traditional near-ultraviolet photolithography technology, there is usually some photoresist residue after development, which affects the performance of the device. Current technology usually requires a combination of photolithography and etching to solve this problem.

[0004] In terms of packaging technology, general AMR sensors are packaged through complex material isolation layers, which requires multiple processes such as photolithography, etching, and deposition during product manufacturing. The manufacturing process is long and there is a risk of damaging the magnetoresistive layer. Summary of the invention

[0005] The object of the present invention is to provide a method for manufacturing an AMR sensor, comprising the following steps:

[0006] 1) Spin-coat photoresist on the surface of the silicon wafer.

[0007] 2) The first photolithography is performed on the glue-coated silicon wafer to obtain a silicon wafer with magnetoresistive strips and shielding strips patterns.

[0008] 3) magnetron sputtering is performed on the silicon wafer engraved with the magnetoresistive strips and shielding strips, and the silicon wafer after magnetron sputtering is debonded to obtain a silicon wafer with a magnetoresistive layer by magnetron sputtering.

[0009] 4) Annealing the silicon wafer with the magnetron sputtering magnetoresistive layer, and spin-coating photoresist on the annealed silicon wafer to obtain a second-coated silicon wafer.

[0010] 5) The silicon wafer coated with the second glue is subjected to a second photolithography to obtain a silicon wafer engraved with an external electrode pattern.

[0011] 6) Thermal evaporation coating is performed on the silicon wafer engraved with the external electrode pattern, and the silicon wafer after thermal evaporation coating is stripped to obtain a silicon wafer with an AMR electrode layer.

[0012] 7) Packaging the silicon wafer with the AMR electrode layer to obtain an AMR sensor.

[0013] Furthermore, in step 1), before spin coating the photoresist, the silicon wafer is cleaned, and the cleaning method includes an inert gas discharge plasma removal method, an acetone and isopropanol ultrasonic cleaning method.

[0014] Furthermore, the photoresist is a mixture of polymethyl methacrylate and anisole.

[0015] Furthermore, the pattern engraved on the silicon wafer engraved with the magnetic resistance strips and shielding strips includes four groups of magnetic resistance strips, a position mark pattern, two direction mark patterns and four shielding strips.

[0016] The position mark pattern is located at the center of the silicon wafer, and two direction mark patterns are respectively arranged at the symmetrical corners of the position mark pattern.

[0017] The first and third groups of magnetic resistance strips are arranged horizontally, and the second and fourth groups of magnetic resistance strips are arranged vertically, and are evenly distributed around the position mark pattern.

[0018] The four groups of magnetic resistance strips are symmetrically distributed in the center, and the outermost side of each group of magnetic resistance strips is a shielding strip.

[0019] Further, in step 2), the step of performing the first photolithography comprises:

[0020] 2.1) Design the photolithography patterns of the magnetic resistance strips and shielding strips.

[0021] 2.2) Expose areas on the silicon wafer other than those with the photolithography pattern.

[0022] 2.3) Develop the exposed silicon wafer.

[0023] The materials used for the development include methyl isobutyl ketone and isopropyl alcohol.

[0024] In step 5), the step of performing a second photolithography comprises:

[0025] 5.1) Design the photolithography pattern of the external electrodes.

[0026] 5.2) Expose areas on the silicon wafer other than those with the photolithography pattern.

[0027] 5.3) Develop the exposed silicon wafer.

[0028] Furthermore, in step 5), when the second photolithography is performed on the second-time-coated silicon wafer, the second-time-coated silicon wafer is aligned with the designed photolithography pattern so that the external electrode is only connected to the corresponding magnetic resistance strip.

[0029] Further, in step 3), the step of obtaining a silicon wafer having a magnetron sputtering magnetoresistive layer comprises:

[0030] 3.1) Evacuate the operating room of the operating equipment.

[0031] 3.2) Introduce argon gas into the operating room of the operating equipment.

[0032] 3.3) Turn on the RF power supply of Ta target for pre-sputtering.

[0033] 3.4) Open the sample baffle and sputter the silicon wafer with the magnetoresistive strips and shielding strips patterned thereon to obtain a silicon wafer with a seed layer.

[0034] 3.5) Turn off the RF power supply of the Ta target and the sample baffle, and turn on the RF power supply of the Permalloy target for pre-sputtering.

[0035] 3.6) Open the sample baffle and sputter the silicon wafer with the seed layer to obtain a Ni 80 Fe 20 layer of silicon wafer.

[0036] 3.7) Turn off the RF power supply of the Permalloy target and the sample baffle, and turn on the RF power supply of the Ta target for pre-sputtering.

[0037] 3.8) Open the sample baffle and 80 Fe 20 The silicon wafer of the layer is sputtered to obtain the silicon wafer after magnetron sputtering.

[0038] 3.9) Debonding the silicon wafer after magnetron sputtering to obtain a silicon wafer with a magnetron sputtering magnetoresistive layer.

[0039] Further, in step 3.9), the step of removing the silicon wafer after magnetron sputtering includes:

[0040] 3.9.1) Place the silicon wafer after magnetron sputtering in a container containing degumming liquid, and use a dropper to blow air on the edge of the silicon wafer to obtain the degummed silicon wafer.

[0041] The degumming solution includes acetone.

[0042] 3.9.2) Observe the silicon wafer after degumming under a microscope to determine whether there is any part that has not been cleaned. If so, proceed to step 3.9.3). If not, a silicon wafer with a magnetron sputtering magnetoresistive layer is obtained.

[0043] 3.9.3) Use ultrasound to clean the silicon wafer after debonding and return to step 3.9.2).

[0044] Further, in step 6), the step of obtaining a silicon wafer having an AMR electrode layer includes:

[0045] 6.1) Place the silver target and the chromium target into the evaporation boat of the evaporation equipment, and place the silicon wafer with the external electrode pattern engraved on it face down on the top of the inner cavity of the evaporation equipment.

[0046] 6.2) Evacuate the inner cavity of the evaporation equipment.

[0047] 6.3) Open the target shutter and the chromium source power supply. When the deposition is stable, open the sample shutter and perform evaporation on the silicon wafer engraved with the external electrode pattern. After the chromium layer is evaporated, close the sample shutter.

[0048] 6.4) Turn off the chromium source power supply and turn on the silver source power supply. When the deposition is stable, open the sample baffle and perform evaporation on the silicon wafer with the chromium layer. After the silver layer is evaporated, close the sample baffle.

[0049] 6.5) Turn off the target baffle and the silver source power supply, take out the silicon wafer with the chromium layer and the silver layer evaporated, and obtain the silicon wafer after thermal evaporation coating.

[0050] 6.6) Debonding the silicon wafer after thermal evaporation coating to obtain a silicon wafer with an AMR electrode layer.

[0051] The steps of debonding the silicon wafer after thermal evaporation coating are as follows:

[0052] 6.6.1) Place the silicon wafer after thermal evaporation coating in a container containing degumming solution, and use a dropper to blow air on the edge of the silicon wafer to obtain the degummed silicon wafer.

[0053] The degumming solution includes acetone.

[0054] 6.6.2) Observe the silicon wafer after degumming under a microscope to determine whether there is any part that has not been cleaned. If so, proceed to step 6.6.3). If not, a silicon wafer with an AMR electrode layer is obtained.

[0055] 6.6.3) Use ultrasound to clean the silicon wafer after debonding and return to step 6.6.2).

[0056] Further, in step 7), the step of obtaining the AMR sensor includes:

[0057] 7.1) Make a PCB sample holder.

[0058] 7.2) Glue the silicon wafer with the AMR electrode layer to the PCB sample holder.

[0059] 7.3) Use indium wire pressure welding to connect the external electrode in the silicon wafer with the AMR electrode layer to the pad of the PCB sample holder. The steps are as follows:

[0060] 7.3.1) Use a welding gun to melt the indium block and the tin bar, mix them, and obtain a molten alloy. Then, apply the molten alloy to the external electrode of the silicon wafer.

[0061] 7.3.2) Insert the enameled wire into the liquid indium and pull out an indium wire.

[0062] 7.3.3) Press the two ends of the indium wire onto the external electrode in the silicon wafer with the AMR electrode layer and the male pad of the PCB sample holder respectively.

[0063] 7.4) Use a packaging shell to package the male tray of the PCB sample tray in an argon-filled environment.

[0064] The packaging shell includes a fence and a cover plate.

[0065] The technical effect of the present invention is unquestionable. The present invention completes the production of AMR sensors through two photolithography steps, thus simplifying the traditional production process of AMR sensors. In terms of packaging technology, the manufactured chip is directly glued to the PCB board, and the external electrodes in the sample with AMR are connected to the pads of the PCB sample holder by indium wire pressure welding, which reduces the production time and the risk of damaging the magnetoresistive layer.

[0066] The present invention relatively simplifies the traditional AMR sensor manufacturing process, and because the electron beam lithography has a higher precision, the present invention also relatively reduces the size of the AMR sensor, and the size of the sensor is only 1 mm×1 mm.

[0067] The AMR sensor designed by the present invention has the advantages of high output performance sensitivity and high precision. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 It is a process flow chart of the present invention;

[0069] Figure 2 Design drawings for magnetoresistive layer lithography;

[0070] Figure 3 Schematic diagram of magnetron sputtering magnetoresistive layer;

[0071] Figure 4 This is a physical picture of a silicon wafer with a magnetron sputtered magnetoresistive layer;

[0072] Figure 5 Photolithography design for electrode layer;

[0073] Figure 6 This is a real picture of the center alignment cross under an electron microscope;

[0074] Figure 7 It is a partial enlarged picture of a silicon wafer engraved with an external electrode pattern;

[0075] Figure 8 This is a photo of the AMR sensor with electrode layer coating completed under an optical microscope;

[0076] Fig. 9 It is a schematic diagram of the AMR sensor; Fig. 9 (a) is a schematic diagram of the PCB sample tray; Fig. 9 (b) is a schematic diagram of a PCB sample support; Fig. 9 (c) is a schematic diagram of the AMR sensor after pressure welding; Fig. 9 (d) Schematic diagram of the AMR sensor mounted on a grounded base;

[0077] Fig.10 A schematic diagram of the drawn PCB design drawing;

[0078] Fig.11 This is a schematic diagram of the fence;

[0079] Fig.12 is a schematic diagram of the cover;

[0080] Fig.13 A schematic diagram of a set of Wheatstone bridges for AMR sensors;

[0081] Fig.14 It is an equivalent circuit diagram of a set of Wheatstone bridge electrical signal outputs;

[0082] Fig.15 This is a schematic diagram of the output performance of the AMR sensor produced in the present invention. DETAILED DESCRIPTION

[0083] The present invention is further described below in conjunction with the embodiments, but it should not be understood that the above subject matter of the present invention is limited to the following embodiments. Without departing from the above technical ideas of the present invention, various substitutions and changes are made according to the common technical knowledge and customary means in the art, which should all be included in the protection scope of the present invention.

[0084] Embodiment 1:

[0085] See also Figures 1 to 15 , a method for manufacturing an AMR sensor, comprising the following steps:

[0086] 1) Spin-coat photoresist on the surface of the silicon wafer.

[0087] 2) The first photolithography is performed on the glue-coated silicon wafer to obtain a silicon wafer with magnetoresistive strips and shielding strips patterns.

[0088] 3) magnetron sputtering is performed on the silicon wafer engraved with the magnetoresistive strips and shielding strips, and the silicon wafer after magnetron sputtering is debonded to obtain a silicon wafer with a magnetoresistive layer by magnetron sputtering.

[0089] 4) Annealing the silicon wafer with the magnetron sputtering magnetoresistive layer, and spin-coating photoresist on the annealed silicon wafer to obtain a second-coated silicon wafer.

[0090] 5) The silicon wafer coated with the second glue is subjected to a second photolithography to obtain a silicon wafer engraved with an external electrode pattern.

[0091] 6) Thermal evaporation coating is performed on the silicon wafer engraved with the external electrode pattern, and the silicon wafer after thermal evaporation coating is stripped to obtain a silicon wafer with an AMR electrode layer.

[0092] 7) Packaging the silicon wafer with the AMR electrode layer to obtain an AMR sensor.

[0093] Embodiment 2:

[0094] A method for manufacturing an AMR sensor, the main technical content of which is shown in Example 1. Further, in step 1), before spin coating the photoresist, the silicon wafer is cleaned, and the cleaning method includes an inert gas discharge plasma removal method, an acetone and isopropanol ultrasonic cleaning method.

[0095] Embodiment 3:

[0096] A method for manufacturing an AMR sensor, the main technical content of which is shown in any one of Examples 1 to 2, further, the photoresist is a mixture of polymethyl methacrylate and anisole.

[0097] Embodiment 4:

[0098] A method for manufacturing an AMR sensor, the main technical content of which is shown in any one of embodiments 1 to 3, further, the pattern engraved on the silicon wafer engraved with magnetic resistance strips and shielding strips includes four groups of magnetic resistance strips, a position mark pattern, two direction mark patterns and four shielding strips.

[0099] The position mark pattern is located at the center of the silicon wafer, and two direction mark patterns are respectively arranged at the symmetrical corners of the position mark pattern.

[0100] The first and third groups of magnetic resistance strips are arranged horizontally, and the second and fourth groups of magnetic resistance strips are arranged vertically, and are evenly distributed around the position mark pattern.

[0101] The four groups of magnetic resistance strips are symmetrically distributed in the center, and the outermost side of each group of magnetic resistance strips is a shielding strip.

[0102] Embodiment 5:

[0103] A method for manufacturing an AMR sensor, the main technical content of which is shown in any one of embodiments 1 to 4, further, in step 2), the step of performing the first photolithography comprises:

[0104] 2.1) Design the photolithography patterns of the magnetic resistance strips and shielding strips.

[0105] 2.2) Expose areas on the silicon wafer other than those with the photolithography pattern.

[0106] 2.3) Develop the exposed silicon wafer.

[0107] The materials used for the development include methyl isobutyl ketone and isopropyl alcohol.

[0108] In step 5), the step of performing a second photolithography comprises:

[0109] 5.1) Design the photolithography pattern of the external electrodes.

[0110] 5.2) Expose areas on the silicon wafer other than those with the photolithography pattern.

[0111] 5.3) Develop the exposed silicon wafer.

[0112] Embodiment 6:

[0113] A method for manufacturing an AMR sensor, the main technical content of which is shown in any one of embodiments 1 to 5. Further, in step 5), when the second photolithography is performed on the second-coated silicon wafer, the second-coated silicon wafer is aligned with the designed photolithography pattern so that the external electrode is only connected to the corresponding magnetic resistance strip.

[0114] Embodiment 7:

[0115] A method for manufacturing an AMR sensor, the main technical content of which is shown in any one of embodiments 1 to 6, further, in step 3), the step of obtaining a silicon wafer having a magnetron sputtering magnetoresistive layer comprises:

[0116] 3.1) Evacuate the operating room of the operating equipment.

[0117] 3.2) Introduce argon gas into the operating room of the operating equipment.

[0118] 3.3) Turn on the RF power supply of Ta target for pre-sputtering.

[0119] 3.4) Open the sample baffle and sputter the silicon wafer with the magnetoresistive strips and shielding strips patterned thereon to obtain a silicon wafer with a seed layer.

[0120] 3.5) Turn off the RF power supply of the Ta target and the sample baffle, and turn on the RF power supply of the Permalloy target for pre-sputtering.

[0121] 3.6) Open the sample baffle and sputter the silicon wafer with the seed layer to obtain a Ni 80 Fe 20 layer of silicon wafer.

[0122] 3.7) Turn off the RF power supply of the Permalloy target and the sample baffle, and turn on the RF power supply of the Ta target for pre-sputtering.

[0123] 3.8) Open the sample baffle and 80 Fe20 The silicon wafer of the layer is sputtered to obtain the silicon wafer after magnetron sputtering.

[0124] 3.9) Debonding the silicon wafer after magnetron sputtering to obtain a silicon wafer with a magnetron sputtering magnetoresistive layer.

[0125] Embodiment 8:

[0126] A method for manufacturing an AMR sensor, the main technical content of which is shown in any one of embodiments 1 to 7, further, in step 3.9), the step of removing the silicon wafer after magnetron sputtering comprises:

[0127] 3.9.1) Place the silicon wafer after magnetron sputtering in a container containing degumming liquid, and use a dropper to blow air on the edge of the silicon wafer to obtain the degummed silicon wafer.

[0128] The degumming solution includes acetone.

[0129] 3.9.2) Observe the silicon wafer after degumming under a microscope to determine whether there is any part that has not been cleaned. If so, proceed to step 3.9.3). If not, a silicon wafer with a magnetron sputtering magnetoresistive layer is obtained.

[0130] 3.9.3) Use ultrasound to clean the silicon wafer after debonding and return to step 3.9.2).

[0131] Embodiment 9:

[0132] A method for manufacturing an AMR sensor, the main technical content of which is shown in any one of embodiments 1 to 8, further, in step 6), the step of obtaining a silicon wafer having an AMR electrode layer comprises:

[0133] 6.1) Place the silver target and the chromium target into the evaporation boat of the evaporation equipment, and place the silicon wafer with the external electrode pattern engraved on it face down on the top of the inner cavity of the evaporation equipment.

[0134] 6.2) Evacuate the inner cavity of the evaporation equipment.

[0135] 6.3) Open the target shutter and the chromium source power supply. When the deposition is stable, open the sample shutter and perform evaporation on the silicon wafer engraved with the external electrode pattern. After the chromium layer is evaporated, close the sample shutter.

[0136] 6.4) Turn off the chromium source power supply and turn on the silver source power supply. When the deposition is stable, open the sample baffle and perform evaporation on the silicon wafer with the chromium layer. After the silver layer is evaporated, close the sample baffle.

[0137] 6.5) Turn off the target baffle and the silver source power supply, take out the silicon wafer with the chromium layer and the silver layer evaporated, and obtain the silicon wafer after thermal evaporation coating.

[0138] 6.6) Debonding the silicon wafer after thermal evaporation coating to obtain a silicon wafer with an AMR electrode layer.

[0139] The steps of debonding the silicon wafer after thermal evaporation coating are as follows:

[0140] 6.6.1) Place the silicon wafer after thermal evaporation coating in a container containing degumming solution, and use a dropper to blow air on the edge of the silicon wafer to obtain the degummed silicon wafer.

[0141] The degumming solution includes acetone.

[0142] 6.6.2) Observe the silicon wafer after degumming under a microscope to determine whether there is any part that has not been cleaned. If so, proceed to step 6.6.3). If not, a silicon wafer with an AMR electrode layer is obtained.

[0143] 6.6.3) Use ultrasound to clean the silicon wafer after debonding and return to step 6.6.2).

[0144] Embodiment 10:

[0145] A method for manufacturing an AMR sensor, the main technical content of which is shown in any one of embodiments 1 to 9, further, in step 7), the step of obtaining the AMR sensor comprises:

[0146] 7.1) Make a PCB sample holder.

[0147] 7.2) Glue the silicon wafer with the AMR electrode layer to the PCB sample holder.

[0148] 7.3) Use indium wire pressure welding to connect the external electrode in the silicon wafer with the AMR electrode layer to the pad of the PCB sample holder. The steps are as follows:

[0149] 7.3.1) Use a welding gun to melt the indium block and the tin bar, mix them, and obtain a molten alloy. Then, apply the molten alloy to the external electrode of the silicon wafer.

[0150] 7.3.2) Insert the enameled wire into the liquid indium and pull out an indium wire.

[0151] 7.3.3) Press the two ends of the indium wire onto the external electrode in the silicon wafer with the AMR electrode layer and the male pad of the PCB sample holder respectively.

[0152] 7.4) Use a packaging shell to package the male tray of the PCB sample tray in an argon-filled environment.

[0153] The packaging shell includes a fence and a cover plate.

[0154] Embodiment 11:

[0155] See also Figures 1 to 15, a method for manufacturing an AMR sensor, comprising the following steps:

[0156] 1) Spin-coat photoresist on the surface of the silicon wafer.

[0157] The glue was coated by rotation, first running at a low speed of 500 rad / min for 2 seconds, and then automatically changing to 5000 rad / min for 50 seconds.

[0158] 2) The first photolithography is performed on the glue-coated silicon wafer to obtain a silicon wafer with magnetoresistive strips and shielding strips patterns.

[0159] 3) magnetron sputtering is performed on the silicon wafer engraved with the magnetoresistive strips and shielding strips, and the silicon wafer after magnetron sputtering is debonded to obtain a silicon wafer with a magnetoresistive layer by magnetron sputtering.

[0160] 4) Annealing the silicon wafer with the magnetron sputtering magnetoresistive layer, and spin-coating photoresist on the annealed silicon wafer to obtain a second-coated silicon wafer.

[0161] For annealing treatment, the sample with the magnetoresistance layer is placed in a small crucible, and then the crucible is placed horizontally in a glass tube with cotton balls plugged at both ends. After evacuation, the tube is sealed with a glass column, and then the glass tube is placed in a constant temperature furnace. The heating rate is set to 2℃ / min, the insulation temperature is set to 350℃, and the insulation time is set to 3.5h.

[0162] 5) The silicon wafer coated with the second glue is subjected to a second photolithography to obtain a silicon wafer engraved with an external electrode pattern.

[0163] 6) Thermal evaporation coating is performed on the silicon wafer engraved with the external electrode pattern, and the silicon wafer after thermal evaporation coating is stripped to obtain a silicon wafer with an AMR electrode layer.

[0164] 7) Packaging the silicon wafer with the AMR electrode layer to obtain an AMR sensor.

[0165] Embodiment 12:

[0166] A method for manufacturing an AMR sensor, the main technical content of which is shown in Example 11. Further, in step 1), before spin coating the photoresist, the silicon wafer is cleaned, and the cleaning method includes an inert gas discharge plasma removal method, an acetone and isopropanol ultrasonic cleaning method.

[0167] The inert gas discharge plasma removal method refers to using inert gas (argon) discharge plasma to remove impurities or pollutants on the surface of the substrate.

[0168] Embodiment 13:

[0169] A method for manufacturing an AMR sensor, the main technical content of which is shown in any one of Examples 11 to 12, further, the photoresist is a mixture of polymethyl methacrylate and anisole.

[0170] PMMA (Polymethyl Methacrylate) photoresist used in photolithography is prepared by fully mixing PMMA powder with anisole to obtain a PMMA photoresist with a mass fraction of 5%.

[0171] Embodiment 14:

[0172] A method for manufacturing an AMR sensor, the main technical content of which is shown in any one of Examples 11 to 13, further, the pattern engraved on the silicon wafer engraved with magnetic resistance strips and shielding strips includes four groups of magnetic resistance strips, a position mark pattern, two direction mark patterns and four shielding strips.

[0173] The position mark pattern is located at the center of the silicon wafer, and two direction mark patterns are respectively arranged at the symmetrical corners of the position mark pattern.

[0174] The position mark pattern and the direction mark pattern are both in a cross shape.

[0175] The first and third groups of magnetic resistance strips are arranged horizontally, and the second and fourth groups of magnetic resistance strips are arranged vertically, and are evenly distributed around the position mark pattern.

[0176] The four groups of magnetic resistance strips are symmetrically distributed in the center, and the outermost side of each group of magnetic resistance strips is a shielding strip.

[0177] Embodiment 15:

[0178] A method for manufacturing an AMR sensor, the main technical content of which is shown in any one of embodiments 11 to 14, further, in step 2), the step of performing the first photolithography comprises:

[0179] 2.1) Design the photolithography patterns of the magnetic resistance strips and shielding strips in QCAD (open source graphic design software).

[0180] 2.2) Expose the area on the silicon wafer other than the photolithography pattern. Set the exposure dose to 180C / cm 2 , beam current is 3.2nA, and magnification is 300 times.

[0181] 2.3) Developing the exposed silicon wafer to dissolve the photoresist at the locations where the photolithography patterns are set on the silicon wafer.

[0182] The materials used for the development include methyl isobutyl ketone and isopropyl alcohol.

[0183] In step 5), the step of performing a second photolithography comprises:

[0184] 5.1) Design the photolithography pattern of the external electrode in QCAD (open source graphic design software).

[0185] 5.2) Expose the area on the silicon wafer other than the photolithography pattern. Set the exposure dose to 180C / cm 2 , beam current is 3.2nA, and magnification is 300 times.

[0186] 5.3) Developing the exposed silicon wafer to dissolve the photoresist at the locations where the photolithography patterns are formed on the silicon wafer.

[0187] The developer is made of methyl isobutyl ketone (MIBK) and isopropyl alcohol in a ratio of 1:3. The development is divided into two steps. First, the exposed silicon wafer is placed in the developer at room temperature for 30 seconds, and it can be gently shaken to promote the dissolution of the photoresist. Then the silicon wafer is immersed in isopropyl alcohol for 30 seconds, the developer is washed off, and finally dried with a nitrogen gun.

[0188] Embodiment 16:

[0189] A method for manufacturing an AMR sensor, the main technical content of which is shown in any one of Examples 11 to 15. Further, in step 5), when the second photolithography is performed on the second-coated silicon wafer, the second-coated silicon wafer is aligned with the designed photolithography pattern so that the external electrode is only connected to the corresponding magnetic resistance strip.

[0190] The cross in the middle is used to align the two photolithography steps. The large cross corrects the position, and the small cross corrects the direction.

[0191] Embodiment 17:

[0192] A method for manufacturing an AMR sensor, the main technical content of which is shown in any one of embodiments 11 to 16, further, the three-layer film structure of the AMR sensor sensing layer is Ta / Ni from bottom to top. 80 Fe 20 / Ta, such as Figure 3 As shown, the bottom Ta layer is the seed layer for Ni 80 Fe 20 The top Ta layer acts as a protective layer to prevent Ni 80 Fe 20 The thickness of the three layers are: Ta 5nm, Permalloy 11nm, Ta 5nm.

[0193] In step 3), the step of obtaining a silicon wafer having a magnetron sputtering magnetoresistive layer comprises:

[0194] 3.1) Evacuate the operating room of the operating equipment.

[0195] 3.2) Introduce argon gas into the operating room of the operating equipment.

[0196] 3.3) Turn on the RF power supply of Ta target for pre-sputtering.

[0197] 3.4) Open the sample baffle and sputter the silicon wafer with the magnetoresistive strips and shielding strips patterned thereon to obtain a silicon wafer with a seed layer.

[0198] 3.5) Turn off the RF power supply of the Ta target and the sample baffle, and turn on the RF power supply of the Permalloy target for pre-sputtering.

[0199] 3.6) Open the sample baffle and sputter the silicon wafer with the seed layer to obtain a Ni 80 Fe 20 layer of silicon wafer.

[0200] 3.7) Turn off the RF power supply of the Permalloy target and the sample baffle, and turn on the RF power supply of the Ta target for pre-sputtering.

[0201] 3.8) Open the sample baffle and 80 Fe 20 The silicon wafer of the layer is sputtered to obtain the silicon wafer after magnetron sputtering.

[0202] 3.9) Debonding the silicon wafer after magnetron sputtering to obtain a silicon wafer with a magnetron sputtering magnetoresistive layer.

[0203] Embodiment 18:

[0204] A method for manufacturing an AMR sensor, the main technical content of which is shown in any one of embodiments 11 to 17, further, in step 3.9), the step of removing the silicon wafer after magnetron sputtering comprises:

[0205] 3.9.1) Place the silicon wafer after magnetron sputtering in a container containing degumming liquid, and use a dropper to blow air on the edge of the silicon wafer to obtain the degummed silicon wafer, and then clean it with isopropyl alcohol.

[0206] The degumming solution includes acetone.

[0207] 3.9.2) Observe the silicon wafer after degumming under a microscope to determine whether there is any part that has not been cleaned. If so, proceed to step 3.9.3). If not, a silicon wafer with a magnetron sputtering magnetoresistive layer is obtained.

[0208] 3.9.3) Use appropriate ultrasonic cleaning to clean the silicon wafer after debonding and return to step 3.9.2).

[0209] Embodiment 19:

[0210] A method for manufacturing an AMR sensor, the main technical content of which is shown in any one of Embodiments 11 to 18, further, in step 6), the step of obtaining a silicon wafer having an AMR electrode layer comprises:

[0211] 6.1) Place the silver target and the chromium target into the evaporation boat of the evaporation equipment, and place the silicon wafer with the external electrode pattern engraved on it face down on the top of the inner cavity of the evaporation equipment.

[0212] 6.2) Evacuate the inner cavity of the evaporation equipment.

[0213] 6.3) Open the target shutter and the chromium source power supply. When the deposition is stable, open the sample shutter and perform evaporation on the silicon wafer engraved with the external electrode pattern. After the chromium layer is evaporated, close the sample shutter.

[0214] 6.4) Turn off the chromium source power supply and turn on the silver source power supply. When the deposition is stable, open the sample baffle and perform evaporation on the silicon wafer with the chromium layer. After the silver layer is evaporated, close the sample baffle.

[0215] 6.5) Turn off the target baffle and the silver source power supply, take out the silicon wafer with the chromium layer and the silver layer evaporated, and obtain the silicon wafer after thermal evaporation coating.

[0216] 6.6) Debonding the silicon wafer after thermal evaporation coating to obtain a silicon wafer with an AMR electrode layer.

[0217] The steps of debonding the silicon wafer after thermal evaporation coating are as follows:

[0218] 6.6.1) Place the silicon wafer after thermal evaporation coating in a container containing degumming solution, and use a dropper to blow air on the edge of the silicon wafer to obtain the degummed silicon wafer, and then clean it with isopropyl alcohol.

[0219] The degumming solution includes acetone.

[0220] 6.6.2) Observe the silicon wafer after degumming under a microscope to determine whether there is any part that has not been cleaned. If so, proceed to step 6.6.3). If not, a silicon wafer with an AMR electrode layer is obtained.

[0221] 6.6.3) Use appropriate ultrasonic cleaning to clean the silicon wafer after debonding and return to step 6.6.2).

[0222] Embodiment 20:

[0223] A method for manufacturing an AMR sensor, the main technical content of which is shown in any one of embodiments 11 to 19, further, in step 7), the step of obtaining the AMR sensor comprises:

[0224] 7.1) Make a PCB sample holder.

[0225] 7.2) Glue the silicon wafer with the AMR electrode layer to the PCB sample holder.

[0226] 7.3) Use indium wire pressure welding to connect the external electrode in the silicon wafer with the AMR electrode layer to the pad of the PCB sample holder. The steps are as follows:

[0227] 7.3.1) Use a welding gun to melt the indium block and the tin bar, mix them, and obtain a molten alloy. Then, apply the molten alloy to the external electrode of the silicon wafer.

[0228] 7.3.2) Insert the enameled wire into the liquid indium and pull out an indium wire.

[0229] 7.3.3) Press the two ends of the indium wire onto the external electrode in the silicon wafer with the AMR electrode layer and the male pad of the PCB sample holder respectively, and connect the pad and the pin through the wire on the PCB sample holder.

[0230] 7.4) Use a packaging shell to package the male tray of the PCB sample tray in an argon-filled environment.

[0231] The packaging shell includes a fence and a cover plate.

[0232] Embodiment 21:

[0233] See also Figures 1 to 15 , a method for manufacturing an AMR sensor, the main technical contents include:

[0234] The main process flows included in this process are:

[0235] (a) cleaning silicon wafers;

[0236] (b) Splicing (PMMA);

[0237] (c) Electron-Beam Lithography (EBL);

[0238] (d) magnetron sputtered magnetoresistive layer (Ta / Fe / Ta);

[0239] (e) degumming and vacuum annealing;

[0240] (f) Glue (PMMA)

[0241] (g) Electron beam lithography (EBL)

[0242] (h) Thermal evaporation coating (Cr / Ag)

[0243] (i) Removal of adhesive;

[0244] (j) Indium wire bonding and packaging;

[0245] 1. PMMA (Polymethyl Methacrylate) photoresist used in photolithography. Fully mix PMMA powder with anisole to prepare PMMA photoresist with a mass fraction of 5%. Plasma treatment is performed before coating, and impurities or pollutants on the surface of the substrate are removed by inert gas (argon) discharge plasma. Then, spin coating is performed, first at a low speed of 500 rad / min for 2 seconds, and then automatically changed to 5000 rad / min for 50 seconds. Import the drawings designed in QCAD (open source graphic design software) into the control computer, and automatically generate the operating file of the photolithography machine after setting the parameters, and set the exposure dose to 180C / cm 2 , beam current is 3.2nA, magnification is 300 times. There are two photolithography processes, the parameters of the second photolithography are the same as the first, so I will not repeat them.

[0246] Figure 2 This is the design drawing of the first photolithography. The long strips (sharp angle, 60°) are magnetic resistance strips. There are four groups of them, symmetrically centered. The outermost strips of each group of magnetic resistance strips are shielding strips to reduce the magnetic field noise in the space. The cross in the middle is used to align the two photolithography. The large cross corrects the position, and the small cross corrects the direction.

[0247] Development. The developer is made of methyl isobutyl ketone (MIBK) and isopropyl alcohol in a ratio of 1:3. Development is divided into two steps. First, place the exposed silicon wafer in the developer at room temperature for 30 seconds. Gently shake it to promote the dissolution of the photoresist. Then soak the silicon wafer in isopropyl alcohol for 30 seconds, wash off the developer, and finally use a nitrogen gun to blow dry.

[0248] After the above steps, the first step of photolithography has been completed, and you can observe under an optical microscope whether the pattern meets expectations and whether there is any residual glue.

[0249] 2. The three-layer film structure of the AMR sensor sensing layer in this design is Ta / Ni from bottom to top. 80 Fe 20 / Ta, such as Figure 3 As shown, the bottom Ta layer is the seed layer for Ni 80 Fe 20 The top Ta layer acts as a protective layer to prevent Ni 80 Fe 20 of oxidation.

[0250] The thickness of the three layers in this experiment are: Ta 5nm, Permalloy 11nm, Ta 5nm; the main steps of magnetron sputtering are: first, evacuate the equipment to 9e with a mechanical pump -1Pa and then open the molecular pump valve (the molecular pump must be accelerated to 24000r / min first), and evacuate to 1e -5 Pa; then introduce argon and control the flow rate to 30sccm; turn on the Ta target RF power supply, DC 89mA, voltage 284V, pre-sputtering for 3mins; then open the sample baffle, and the sputtering time is 59s.

[0251] Turn off the RF power supply and sample baffle of the Ta target, and turn on the RF power supply of the Permalloy target, DC 76mA, voltage 399V; open the sample baffle after pre-sputtering for 3mins, and the sputtering time is 177s; the operation of the last layer of Ta is the same as above.

[0252] During the magnetron sputtering process, excess metal will be plated on the PMMA surface. At this time, a solvent is used to dissolve the PMMA, and the metal film on the surface will fall off. The solvent used for degumming is acetone. The method is as follows: Place the silicon wafer in a container filled with acetone, and use a dropper to continuously "blow" on the edge of the silicon wafer (blow once every 30 minutes). After 4 hours, all the excess metal can be washed off and placed under a microscope for inspection. If there are any parts that have not been washed off, use ultrasonic cleaning as appropriate. The magnetoresistive layer after degumming is as follows Figure 4 shown.

[0253] 3. Annealing treatment: put the sample with magnetoresistance layer into a small crucible, and then put the crucible horizontally into a glass tube with cotton balls plugged at both ends. After evacuating, seal the tube with a glass column, and then put the glass tube into a constant temperature furnace. Set the heating rate to 2℃ / min, the insulation temperature to 350℃, and the insulation time to 3.5h.

[0254] 4 The photolithography steps of the second photolithography electrode layer are basically the same as the first one, but the photolithography of the second layer strictly requires alignment with the pattern of the first layer. In order to achieve this goal, this paper adopts the following method:

[0255] When designing the first layer, mark points are left in the center as shown in the figure below. By adjusting the position and direction of the large cross, the graphics can be accurately aligned.

[0256] Figure 5 For design drawings, the small crosses on both sides are used to mark the direction. Figure 6 This is the center alignment cross under 10,000 times magnification of the electron microscope. By adjusting the position and direction so that it coincides with the center mark of the field of view, the two layers of patterns can be accurately aligned, such as Figure 7 shown.

[0257] 5. Thermal evaporation coating of the AMR electrode layer: silver target and chromium target are placed in the evaporation boat, and then the silicon wafer is placed with the front side facing down and the back side adhered to the tray, and placed above the internal cavity of the equipment; vacuum is drawn. First, the mechanical pump is turned on to pump the air pressure in the cabin to 1e-1 Pa, then turn on the molecular pump power supply, open the molecular pump valve when the molecular pump speed reaches 24000r / min, until the vacuum degree of the equipment reaches 5×10-6Torr, start operation, chromium as the seed layer, evaporate 5nm, open the target baffle, turn on the chromium source power supply, set the current to 160A, open the sample baffle when the panel shows deposition, click the sample rotation button and return the thickness to zero, the instrument automatically monitors the thickness, close the sample baffle to stop the sample rotation when the thickness is displayed as 5nm, turn off the chromium source, and close the chromium source baffle. Silver plating 40nm, open the target baffle, turn on the silver source power supply, set the current to 60A, open the sample baffle when the panel shows deposition, click the sample rotation button and return the thickness to zero, the instrument automatically monitors the thickness, close the sample baffle to stop the sample rotation when the thickness is displayed as 40nm, turn off the silver source, and close the silver source baffle. After completion, remove the silicon wafer and evacuate the air in the device. During the magnetron sputtering process, excess metal will be plated on the PMMA surface. At this time, a solvent is used to dissolve the PMMA, and the metal film on the surface will fall off. The solvent used for degumming is acetone. The method is as follows: introduce a sufficient amount of acetone into the container, immerse the silicon wafer completely in it, seal the container mouth with a plastic film to prevent the acetone from volatilizing, and let it stand for a while. When the surface of the metal film peels and becomes uneven, gently shake the container to peel off the metal film. When the metal is difficult to peel off, consider using ultrasonic equipment to complete the peeling. The result after degumming is completed is as follows Figure 8 As shown:

[0258] 6. Indium wire pressure welding and packaging. The packaged device consists of a housing, a PCB sample holder, and an indium connecting wire. The PCB sample holder is designed to be a pluggable structure consisting of a male holder and a female holder (the male holder is welded with pins, the female holder is welded with a jack, and the jack is connected to the external circuit). The indium connecting wire can connect the sample with AMR to the pad of the PCB sample holder, and then connect to the pin. Fig. 9 They are: a) male PCB sample holder; b) female PCB sample holder; c) AMR sensor after pressure welding; d) AMR sensor mounted on a grounded base.

[0259] The PCB board drawn in Altium Designer is as follows Fig.10 As shown in the figure, the PCB sample tray is manufactured by Shenzhen Jiali Chuang, and the pins are soldered on the manufactured PCB.

[0260] Indium pressure connection: The manufactured chip is glued to the reserved position in the PCB board. At this time, indium wire is needed to be pressed to connect the external electrode in the sample with AMR to the pad of the PCB sample holder.

[0261] The indium pressing process is as follows:

[0262] 1) Melt a small amount of indium block and tin bar with a welding gun and mix them together, then use the welding gun to apply the molten alloy to the electrodes around the chip;

[0263] 2) Take a small amount of indium block and melt it with a welding torch and keep it melted. Use a section of enameled wire to extend into the liquid indium and slowly pull out an indium wire with a thin head and thick body and a suitable length.

[0264] 3) Press the two ends of the indium wire onto the lead-out electrode of the chip and the pad of the PCB respectively under a microscope;

[0265] Assembly: The male tray is packaged in a glove box filled with argon to prevent the components in the air from oxidizing the resistance part of the magnetic sensing element and affecting the performance of the magnetic sensing element. The package shell is divided into two parts: the fence and the cover. The fence is made by 3D printing, and the cover is a quartz plate. Figure 11-12 shown.

[0266] The output mode of the AMR sensor: The sensor uses two sets of Wheatstone bridges to output electrical signals, which can represent the magnitude components of the magnetic field in two orthogonal directions in a plane. Fig.13 As shown:

[0267] Where V DD is the power supply voltage, GND is the ground, is a set of differential voltages.

[0268] The equivalent circuit diagram is as follows Fig.14 As shown, the external magnetic field is perpendicular to the four magnetic resistance strips and is upward. R1 = R4 = R + ΔR, R2 = R3 = R - ΔR.

[0269] Output:

[0270] This design relatively simplifies the traditional AMR sensor manufacturing process, and because electron beam lithography has higher precision, this design also relatively reduces the size of the AMR sensor, with the widest part being only 1 mm.

[0271] The output performance of the AMR sensor designed in this paper is as follows Fig.15 As shown:

[0272] Its sensitivity is 0.109mV / V / Oe and its maximum accuracy is 0.033Oe.

Claims

1. A method for manufacturing an AMR sensor, characterized in that: The following steps are involved: 1) Spin-coating photoresist on the surface of silicon wafer; 2) Performing the first photolithography on the coated silicon wafer to obtain a silicon wafer with magnetoresistive strips and shielding strips patterns; 3) magnetron sputtering is performed on the silicon wafer engraved with the magnetoresistive strips and shielding strips, and the silicon wafer after magnetron sputtering is debonded to obtain a silicon wafer with a magnetoresistive layer by magnetron sputtering. 4) annealing the silicon wafer with the magnetron sputtering magnetoresistive layer, and spin coating photoresist on the annealed silicon wafer to obtain a secondary coated silicon wafer; 5) performing a second photolithography on the silicon wafer coated with the second glue to obtain a silicon wafer engraved with an external electrode pattern; 6) Thermal evaporation coating is performed on the silicon wafer engraved with the external electrode pattern, and the silicon wafer after thermal evaporation coating is stripped to obtain a silicon wafer with an AMR electrode layer. 7) Packaging the silicon wafer with the AMR electrode layer to obtain an AMR sensor.

2. The method for manufacturing an AMR sensor according to claim 1, characterized in that: In step 1), before spin coating the photoresist, the silicon wafer is also cleaned, and the cleaning method includes an inert gas discharge plasma removal method, an acetone and isopropanol ultrasonic cleaning method.

3. The method for manufacturing an AMR sensor according to claim 1, characterized in that: The photoresist is a mixture of polymethyl methacrylate and anisole.

4. The method for manufacturing an AMR sensor according to claim 1, characterized in that: The pattern engraved on the silicon wafer engraved with the magnetic resistance strips and shielding strips includes four groups of magnetic resistance strips, a position mark pattern, two direction mark patterns and four shielding strips; The position mark pattern is located at the center of the silicon wafer, and two direction mark patterns are respectively arranged at the symmetrical angles of the position mark pattern; The first and third groups of magnetic resistance strips are arranged horizontally, and the second and fourth groups of magnetic resistance strips are arranged vertically, and are evenly distributed around the position marking pattern; The four groups of magnetic resistance strips are symmetrically distributed in the center, and the outermost side of each group of magnetic resistance strips is a shielding strip.

5. The method for manufacturing an AMR sensor according to claim 1, characterized in that: In step 2), the first photolithography step includes: 2.1) Design the photolithography patterns of the magnetic resistance strips and shielding strips; 2.2) Exposing the area on the silicon wafer other than the photolithography pattern; 2.3) Developing the exposed silicon wafer; The materials used for the development include methyl isobutyl ketone and isopropyl alcohol; In step 5), the step of performing a second photolithography comprises: 5.1) Design the photolithography pattern of the external electrodes; 5.2) Exposing the area on the silicon wafer other than the photolithography pattern; 5.3) Develop the exposed silicon wafer.

6. The method for manufacturing an AMR sensor according to claim 1, characterized in that: In step 5), when the second photolithography is performed on the silicon wafer coated with the second glue, the silicon wafer coated with the second glue is aligned with the designed photolithography pattern so that the external electrode is only connected to the corresponding magnetic resistance strip.

7. The method for manufacturing an AMR sensor according to claim 1, characterized in that: In step 3), the step of obtaining a silicon wafer having a magnetron sputtering magnetoresistive layer comprises: 3.1) Evacuate the operating room of the operating equipment; 3.2) Introduce argon gas into the operating room of the operating equipment; 3.3) Turn on the RF power supply of Ta target for pre-sputtering; 3.4) Open the sample baffle and sputter the silicon wafer with the magnetoresistive strips and shielding strips patterned thereon to obtain a silicon wafer with a seed layer; 3.5) Turn off the RF power supply of the Ta target and the sample baffle, and turn on the RF power supply of the Permalloy target for pre-sputtering; 3.6) Open the sample baffle and sputter the silicon wafer with the seed layer to obtain a Ni 80 Fe 20 layer of silicon wafer; 3.7) Turn off the RF power supply and sample baffle of the Permalloy target, and turn on the RF power supply of the Ta target for pre-sputtering; 3.8) Open the sample baffle and 80 Fe 20 The silicon wafer of the layer is sputtered to obtain the silicon wafer after magnetron sputtering; 3.9) Debonding the silicon wafer after magnetron sputtering to obtain a silicon wafer with a magnetron sputtering magnetoresistive layer.

8. The method for manufacturing an AMR sensor according to claim 7, characterized in that: In step 3.9), the step of removing the silicon wafer after magnetron sputtering includes: 3.9.1) Place the silicon wafer after magnetron sputtering in a container containing degumming liquid, and use a dropper to blow air on the edge of the silicon wafer to obtain the degummed silicon wafer; The degumming solution includes acetone; 3.9.2) Observe the silicon wafer after debonding under a microscope to determine whether there is any part that has not been cleaned. If so, proceed to step 3.9.3); if not, a silicon wafer with a magnetron sputtering magnetoresistive layer is obtained; 3.9.3) Use ultrasound to clean the silicon wafer after debonding and return to step 3.9.2).

9. The method for manufacturing an AMR sensor according to claim 1, characterized in that: In step 6), the step of obtaining a silicon wafer having an AMR electrode layer includes: 6.1) Place the silver target and the chromium target into the evaporation boat of the evaporation equipment, and place the silicon wafer with the external electrode pattern engraved on it face down on the top of the inner cavity of the evaporation equipment; 6.2) Evacuate the inner cavity of the evaporation equipment; 6.3) Turn on the target baffle and the chromium source power supply. When the deposition is stable, open the sample baffle and perform evaporation on the silicon wafer engraved with the external electrode pattern. After the chromium layer is evaporated, close the sample baffle; 6.4) Turn off the chromium source power supply, turn on the silver source power supply, and when the deposition is stable, open the sample baffle to perform evaporation on the silicon wafer with the chromium layer. After the evaporation of the silver layer is completed, close the sample baffle; 6.5) Turn off the target baffle and the silver source power supply, take out the silicon wafer with the chromium layer and the silver layer deposited, and obtain the silicon wafer after thermal evaporation coating; 6.6) Debonding the silicon wafer after thermal evaporation coating to obtain a silicon wafer with an AMR electrode layer; The steps of debonding the silicon wafer after thermal evaporation coating are as follows: 6.6.1) Place the silicon wafer after thermal evaporation coating in a container containing degumming solution, and use a dropper to blow air on the edge of the silicon wafer to obtain the degummed silicon wafer; The degumming solution includes acetone; 6.6.2) Observe the silicon wafer after degumming under a microscope to determine whether there is any part that has not been cleaned. If so, proceed to step 6.6.3); if not, a silicon wafer with an AMR electrode layer is obtained; 6.6.3) Use ultrasound to clean the silicon wafer after debonding and return to step 6.6.2).

10. The method for manufacturing an AMR sensor according to claim 1, characterized in that: In step 7), the step of obtaining the AMR sensor includes: 7.1) Make PCB sample holder; 7.2) Glue the silicon wafer with the AMR electrode layer to the PCB sample holder; 7.3) Use indium wire pressure welding to connect the external electrode in the silicon wafer with the AMR electrode layer to the pad of the PCB sample holder. The steps are as follows: 7.3.1) Use a welding torch to melt the indium block and the tin bar, mix them, and obtain a molten alloy, and then apply the molten alloy to the external electrode of the silicon wafer; 7.3.2) Insert the enameled wire into the liquid indium and draw out an indium wire; 7.3.3) Press the two ends of the indium wire onto the external electrode in the silicon wafer with the AMR electrode layer and the male pad of the PCB sample holder respectively; 7.4) Using a packaging shell to package the male tray of the PCB sample tray in an environment filled with argon gas; The packaging shell includes a fence and a cover plate.

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