A manufacturing method of an AMR sensor

Abstract

A manufacturing method of an AMR sensor comprises the following steps: 1) spin coating photoresist on the surface of a silicon wafer; 2) performing first photoetching on the silicon wafer coated with the photoresist to obtain a silicon wafer with magnetoresistance strip and shielding strip patterns; 3) performing magnetron sputtering on the silicon wafer with the magnetoresistance strip and shielding strip patterns, and removing the photoresist from the silicon wafer after the magnetron sputtering to obtain a silicon wafer with a magnetron sputtered magnetoresistance layer; 4) performing annealing on the silicon wafer with the magnetron sputtered magnetoresistance layer, and spin coating photoresist on the silicon wafer after the annealing to obtain a silicon wafer coated with the photoresist for the second time; 5) performing second photoetching on the silicon wafer coated with the photoresist for the second time to obtain a silicon wafer with an external electrode pattern; 6) performing thermal evaporation plating on the silicon wafer with the external electrode pattern, and removing the photoresist from the silicon wafer after the thermal evaporation plating 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. The present application simplifies the manufacturing process of a conventional AMR sensor. The present application reduces the size of the AMR sensor.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of integrated circuit manufacturing, and particularly relates to a manufacturing method of an AMR sensor. BACKGROUND

[0002] Photoetching technology is a process technology of transferring circuit patterns onto single crystal surface or dielectric layer by using optical-chemical reaction principle and chemical and physical etching methods to form effective pattern window or functional pattern. With the development of semiconductor technology, the size limit of photoetching technology is reduced by 2-3 orders of magnitude (from millimeter level to sub-micron level), and the technology has developed from conventional optical technology to new technologies such as electron beam, X-ray, micro-ion beam and laser; and the wavelength has been expanded from 4000 angstroms to 0.1 angstroms. Photoetching technology has become a precise microfabrication technology.

[0003] In the traditional process, the AMR sensor needs to be photoetched to realize the formation of the predefined pattern. However, due to the low development precision in the traditional near-ultraviolet photoetching technology, there are usually some photoresist residues after development, which affects the performance of the device. The current technology usually needs to combine photoetching and etching to solve this problem.

[0004] In the packaging process, the general AMR sensor is packaged by a complex material isolation layer, which requires multiple photoetching, etching and deposition processes in product manufacturing, and the manufacturing process is long and there is a risk of damaging the magnetic resistance layer. SUMMARY

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

[0006] 1) spin coating photoresist on the surface of a silicon wafer.

[0007] 2) photoetching the silicon wafer coated with photoresist for the first time to obtain a silicon wafer with magnetic resistance strip and shielding strip patterns.

[0008] 3) magnetron sputtering the silicon wafer with magnetic resistance strip and shielding strip patterns, and removing the photoresist from the silicon wafer after magnetron sputtering to obtain a silicon wafer with a magnetron sputtered magnetic resistance layer.

[0009] 4) annealing the silicon wafer with the magnetron sputtered magnetic resistance layer, and spin coating photoresist on the annealed silicon wafer to obtain a silicon wafer coated with photoresist for the second time.

[0010] 5) second photoetching the silicon wafer coated with photoresist for the second time to obtain a silicon wafer with external electrode patterns.

[0011] 6) thermal evaporation plating of the silicon wafer with external electrode patterns, and removing the photoresist from the silicon wafer after thermal evaporation plating to obtain a silicon wafer with an AMR electrode layer.

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

[0013] Further, before the spin-coating of the photoresist, the silicon wafer is cleaned, and the cleaning method includes inert gas discharge plasma removal method and acetone and isopropyl alcohol ultrasonic cleaning method.

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

[0015] Further, the pattern engraved on the silicon wafer includes four groups of AMR strips, a position marker pattern, two direction marker patterns, and four shield strips.

[0016] The position marker pattern is located at the center of the silicon wafer, and two direction marker patterns are respectively arranged at the symmetric angles of the position marker pattern.

[0017] The first group and the third group of AMR strips are arranged horizontally, and the second group and the fourth group of AMR strips are arranged vertically, and are uniformly distributed around the position marker pattern.

[0018] The four groups of AMR strips are symmetrically distributed at the center, and the outermost side of each group of AMR strips is a shield strip.

[0019] Further, in step 2), the step of first photoetching includes:

[0020] 2.1) designing a photoetching pattern of AMR strips and shield strips.

[0021] 2.2) exposing the silicon wafer except the part provided with the photoetching pattern.

[0022] 2.3) developing the exposed silicon wafer.

[0023] The developing material includes methyl isobutyl ketone and isopropyl alcohol.

[0024] In step 5), the step of second photoetching includes:

[0025] 5.1) designing a photoetching pattern of the outer electrode.

[0026] 5.2) exposing the silicon wafer except the part provided with the photoetching pattern.

[0027] 5.3) developing the exposed silicon wafer.

[0028] Further, in step 5), when the twice-coated silicon wafer is subjected to the second photoetching, the twice-coated silicon wafer is aligned with the designed photoetching pattern, so that the outer electrode only communicates with the corresponding AMR strip.

[0029] Further, in step 3), the step of obtaining the silicon wafer with the magnetron sputtering magnetic resistance layer comprises:

[0030] 3.1) Vacuumize the operation chamber of the operation device.

[0031] 3.2) Introduce argon into the operation chamber of the operation device.

[0032] 3.3) Turn on the radio frequency power supply of the Ta target material to perform pre-sputtering.

[0033] 3.4) Open the sample shutter, and sputter the silicon wafer with the magnetic resistance bar and shielding bar pattern to obtain the silicon wafer with the seed layer.

[0034] 3.5) Turn off the radio frequency power supply of the Ta target material and the sample shutter, and turn on the radio frequency power supply of the permalloy target material to perform pre-sputtering.

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

[0036] 3.7) Turn off the radio frequency power supply of the permalloy target material and the sample shutter, and turn on the radio frequency power supply of the Ta target material to perform pre-sputtering.

[0037] 3.8) Open the sample shutter, and sputter the silicon wafer with the Ni 80 Fe 20 layer to obtain the silicon wafer after magnetron sputtering.

[0038] 3.9) Perform de-gluing on the silicon wafer after magnetron sputtering to obtain the silicon wafer with the magnetron sputtering magnetic resistance layer.

[0039] Further, in step 3.9), the step of performing de-gluing on the silicon wafer after magnetron sputtering comprises:

[0040] 3.9.1) Place the silicon wafer after magnetron sputtering in a container containing de-gluing liquid, and blow gas on the edge of the silicon wafer with a dropper to obtain the silicon wafer after de-gluing.

[0041] The de-gluing liquid comprises acetone.

[0042] 3.9.2) Observe the silicon wafer after de-gluing through a microscope to determine whether there is a part that has not been cleaned, if yes, proceed to step 3.9.3), if no, obtain the silicon wafer with the magnetron sputtering magnetic resistance layer.

[0043] 3.9.3) Clean the silicon wafer after de-gluing with ultrasonic waves, and return to step 3.9.2).

[0044] Further, in step 6), the step of obtaining the silicon wafer with the AMR electrode layer comprises:

[0045] 6.1) Put silver target and chromium target into evaporation boat of evaporation equipment, and place silicon wafer with pattern of external electrode on top of inner cavity of evaporation equipment.

[0046] 6.2) Vacuumize inner cavity of evaporation equipment.

[0047] 6.3) Open target shutter and chromium source power supply, and when deposition is stable, open sample shutter, and evaporate on silicon wafer with pattern of external electrode, and after chromium layer is evaporated, close sample shutter.

[0048] 6.4) Close chromium source power supply, and open silver source power supply, and when deposition is stable, open sample shutter, and evaporate on silicon wafer with chromium layer, and after silver layer is evaporated, close sample shutter.

[0049] 6.5) Close target shutter and silver source power supply, and take out silicon wafer with chromium layer and silver layer, and obtain silicon wafer after thermal evaporation plating.

[0050] 6.6) Remove glue from silicon wafer after thermal evaporation plating, and obtain silicon wafer with AMR electrode layer.

[0051] The step of removing glue from silicon wafer after thermal evaporation plating is as follows:

[0052] 6.6.1) Place silicon wafer after thermal evaporation plating in a container containing glue removal liquid, and blow gas on edge of silicon wafer by using dropper, and obtain silicon wafer after glue removal.

[0053] The glue removal liquid comprises acetone.

[0054] 6.6.2) Observe silicon wafer after glue removal by using microscope, and determine whether there is part not cleaned, and if yes, go to step 6.6.3), and if no, obtain silicon wafer with AMR electrode layer.

[0055] 6.6.3) Clean silicon wafer after glue removal by using ultrasonic cleaning, and return to step 6.6.2).

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

[0057] 7.1) Make PCB sample holder.

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

[0059] 7.3) Connect external electrode in silicon wafer with AMR electrode layer and pad of PCB sample holder by using indium wire pressure welding, and the step is as follows:

[0060] 7.3.1) Melt indium block and tin bar by using soldering gun, mix them, obtain molten alloy, and then point molten alloy on external electrode of silicon wafer.

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

[0062] 7.3.3) Press the two ends of the indium wire on 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) Package the male holder of the PCB sample holder in an argon-filled environment by using a packaging shell.

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

[0065] The technical effect of the present application is self-evident, the present application completes the production of the AMR sensor by twice photolithography, simplifies the traditional AMR sensor production process. In the packaging process, the prepared chip is directly glued to the PCB board, and the indium wire is connected with the external electrode in the sample with AMR and the pad of the PCB sample holder, which reduces the production time and reduces the risk of damaging the magnetic resistance layer.

[0066] The present application simplifies the traditional AMR sensor production process, and due to the higher precision of electron beam lithography, the present application also relatively reduces the size of the AMR sensor, and the size of the sensor is only 1mm*1mm.

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

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

[0069] Figure 2 It is a magnetic resistance layer photolithography design drawing;

[0070] Figure 3 It is a schematic diagram of magnetron sputtering magnetic resistance layer;

[0071] Figure 4 It is a silicon wafer with magnetron sputtering magnetic resistance layer;

[0072] Figure 5 It is an electrode layer photolithography design drawing;

[0073] Figure 6 It is a real object drawing of center alignment cross under an electron microscope;

[0074] Figure 7 It is a partial enlarged view of the silicon wafer with external electrode pattern;

[0075] Figure 8 It is a real object drawing of the AMR sensor with completed electrode layer plating film under an optical microscope;

[0076] Figure 9 Fig. 19 is a schematic view of an AMR sensor; Figure 9 Fig. 20 is a schematic view of a PCB sample holder; Figure 9 Fig. 21 is a schematic view of a PCB sample holder; Figure 9 Fig. 22 is a schematic view of an AMR sensor after compression welding; Figure 9 Fig. 23 is a schematic view of an AMR sensor placed on a grounding base;

[0077] Figure 10 Fig. 24 is a schematic view of a designed PCB drawing;

[0078] Figure 11 Fig. 25 is a schematic view of a fence;

[0079] Figure 12 Fig. 26 is a schematic view of a cover plate;

[0080] Figure 13 Fig. 27 is a schematic view of a set of Wheatstone bridges of an AMR sensor;

[0081] Figure 14 Fig. 28 is an equivalent circuit diagram of electrical signal output of a set of Wheatstone bridges;

[0082] Figure 15 Fig. 29 is a schematic view of output performance of an AMR sensor made according to the present application. DETAILED DESCRIPTION

[0083] The present application will be further described below in conjunction with examples, but should not be understood as limiting the above-mentioned subject matter of the present application to the following examples. Various replacements and modifications can be made according to ordinary technical knowledge and conventional means in the art without departing from the above-mentioned technical idea of the present application, and all of them should be included in the protection scope of the present application.

[0084] Example 1

[0085] Referring to Figures 1 to 15 A method for making an AMR sensor, comprising the following steps:

[0086] 1) spin coating photoresist on the surface of a silicon wafer.

[0087] 2) performing first photoetching on the silicon wafer coated with photoresist to obtain a silicon wafer with patterns of magnetoresistance strips and shielding strips.

[0088] 3) performing magnetron sputtering on the silicon wafer with patterns of magnetoresistance strips and shielding strips, and performing photoresist removal on the silicon wafer after magnetron sputtering to obtain a silicon wafer with a magnetron sputtered magnetoresistance layer.

[0089] 4) performing annealing treatment on the silicon wafer with a magnetron sputtered magnetoresistance layer, and spin coating photoresist on the silicon wafer after annealing to obtain a silicon wafer coated with photoresist for the second time.

[0090] 5) Second photoetching is performed on the twice-coated silicon wafer to obtain a silicon wafer with an external electrode pattern.

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

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

[0093] Embodiment 2:

[0094] A manufacturing method of an AMR sensor, the main technical content of which is seen in Embodiment 1, further, before spin coating the photoresist, the silicon wafer is also cleaned, and the cleaning method includes inert gas discharge plasma removal method, acetone and isopropyl alcohol ultrasonic cleaning method.

[0095] Embodiment 3:

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

[0097] Embodiment 4:

[0098] A manufacturing method of an AMR sensor, the main technical content of which is seen in any one of Embodiments 1 to 3, further, the pattern engraved on the silicon wafer with the magnetoresistance strip and the shielding strip pattern includes four groups of magnetoresistance strips, a position marker pattern, two direction marker patterns, and four shielding strips.

[0099] The position marker pattern is located at the center of the silicon wafer, and two direction marker patterns are respectively arranged on the symmetric angles of the position marker pattern.

[0100] The first group and the third group of magnetoresistance strips are arranged horizontally, and the second group and the fourth group of magnetoresistance strips are arranged vertically, and are uniformly distributed around the position marker pattern.

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

[0102] Embodiment 5:

[0103] A manufacturing method of an AMR sensor, the main technical content of which is seen in any one of Embodiments 1 to 4, further, in step 2), the step of performing the first photoetching includes:

[0104] 2.1) Designing a photoetching pattern of magnetoresistance strips and shielding strips.

[0105] 2.2) Exposing the places on the silicon wafer other than the photoetching pattern.

[0106] 2.3) Develop the exposed silicon wafer.

[0107] The material used in the developing includes methyl isobutyl ketone and isopropyl alcohol.

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

[0109] 5.1) Design a photolithography pattern for the outer connecting electrode.

[0110] 5.2) Expose the silicon wafer except the part provided with the photolithography pattern.

[0111] 5.3) Develop the exposed silicon wafer.

[0112] Example 6:

[0113] A method for manufacturing an AMR sensor, the main technical content of which is seen in any one of Examples 1 to 5, further, in step 5), when performing the second photolithography on the twice-glued silicon wafer, the twice-glued silicon wafer is aligned with the designed photolithography pattern, so that the outer connecting electrode only communicates with the corresponding magnetic resistance strip.

[0114] Example 7:

[0115] A method for manufacturing an AMR sensor, the main technical content of which is seen in any one of Examples 1 to 6, further, in step 3), the step of obtaining the silicon wafer with the magnetron sputtered magnetic resistance layer includes:

[0116] 3.1) Vacuumize the operation chamber of the operation device.

[0117] 3.2) Introduce argon into the operation chamber of the operation device.

[0118] 3.3) Turn on the radio frequency power supply of the Ta target material to perform pre-sputtering.

[0119] 3.4) Open the sample shutter, and sputter the silicon wafer provided with the magnetic resistance strip and shielding strip pattern to obtain the silicon wafer with the seed layer.

[0120] 3.5) Turn off the radio frequency power supply of the Ta target material and the sample shutter, and turn on the radio frequency power supply of the permalloy target material to perform pre-sputtering.

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

[0122] 3.7) Turn off the radio frequency power supply of the permalloy target material and the sample shutter, and turn on the radio frequency power supply of the Ta target material to perform pre-sputtering.

[0123] 3.8) Open the sample shutter, and sputter the silicon wafer with the Ni 80 Fe20 The silicon wafer is sputtered to obtain a magnetron sputtered silicon wafer.

[0124] 3.9) The magnetron sputtered silicon wafer is degreased to obtain a silicon wafer with a magnetron sputtered magnetic resistance layer.

[0125] Example 8:

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

[0127] 3.9.1) The magnetron sputtered silicon wafer is placed in a container containing a degreasing solution, and a dropper is used to blow gas at the edge of the silicon wafer to obtain a degreased silicon wafer.

[0128] The degreasing solution comprises acetone.

[0129] 3.9.2) The degreased silicon wafer is observed under a microscope to determine whether there are any parts that have not been cleaned, if so, proceed to step 3.9.3), if not, obtain a silicon wafer with a magnetron sputtered magnetic resistance layer.

[0130] 3.9.3) The degreased silicon wafer is cleaned by ultrasonic cleaning and returned to step 3.9.2).

[0131] Example 9:

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

[0133] 6.1) The silver target and the chromium target are placed in the evaporation boat of the evaporation device, and the silicon wafer with the external electrode pattern is placed on the top of the evaporation device cavity with the external electrode pattern facing down.

[0134] 6.2) The evaporation device cavity is evacuated.

[0135] 6.3) The target shutter and the chromium source power supply are turned on, and when the deposition is stable, the sample shutter is opened, and evaporation is performed on the silicon wafer with the external electrode pattern, after the chromium layer is deposited, the sample shutter is closed.

[0136] 6.4) The chromium source power supply is turned off, the silver source power supply is turned on, and when the deposition is stable, the sample shutter is opened, and evaporation is performed on the silicon wafer with the chromium layer, after the silver layer is deposited, the sample shutter is closed.

[0137] 6.5) The target shutter and the silver source power supply are turned off, and the silicon wafer with the chromium layer and the silver layer is taken out to obtain a silicon wafer after thermal evaporation plating.

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

[0139] The step of degumming the silicon wafer after thermal evaporation plating is as follows:

[0140] 6.6.1) placing the silicon wafer after thermal evaporation plating in a container containing a degumming solution, and blowing gas at the edge of the silicon wafer with a dropper to obtain a degummed silicon wafer.

[0141] The degumming solution comprises acetone.

[0142] 6.6.2) observing the degummed silicon wafer under a microscope to determine whether there are parts that have not been cleaned, and if so, proceeding to step 6.6.3); if not, obtaining a silicon wafer with an AMR electrode layer.

[0143] 6.6.3) ultrasonically cleaning the degummed silicon wafer and returning to step 6.6.2).

[0144] Example 10:

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

[0146] 7.1) manufacturing a PCB sample holder.

[0147] 7.2) gluing the silicon wafer with an AMR electrode layer into the PCB sample holder.

[0148] 7.3) connecting the external electrodes in the silicon wafer with an AMR electrode layer to the pads of the PCB sample holder by means of indium wire pressure welding, the steps being as follows:

[0149] 7.3.1) melting an indium block and a tin bar and mixing them to obtain a molten alloy, and then dotting the molten alloy on the external electrodes of the silicon wafer.

[0150] 7.3.2) inserting an enameled wire into the liquid indium and pulling out an indium wire.

[0151] 7.3.3) pressing the two ends of the indium wire onto the external electrodes in the silicon wafer with an AMR electrode layer and the male pads of the PCB sample holder, respectively.

[0152] 7.4) encapsulating the male holder of the PCB sample holder in an argon-filled environment by means of an encapsulation shell.

[0153] The encapsulation shell comprises a fence and a cover plate.

[0154] Example 11:

[0155] See Figures 1 to 15The application discloses a manufacturing method of an AMR sensor.

[0156] 1) spin coating photoresist on the surface of a silicon wafer.

[0157] The spin coating is performed in the following manner: first, running at a low speed of 500 rad / min for 2 s, and then automatically changing to running at a speed of 5000 rad / min for 50 s.

[0158] 2) performing first photoetching on the silicon wafer coated with the photoresist to obtain a silicon wafer with magnetoresistance strip and shielding strip patterns.

[0159] 3) performing magnetron sputtering on the silicon wafer with the magnetoresistance strip and shielding strip patterns, and performing photoresist removing on the silicon wafer after the magnetron sputtering to obtain a silicon wafer with a magnetron sputtering magnetoresistance layer.

[0160] 4) performing annealing treatment on the silicon wafer with the magnetron sputtering magnetoresistance layer, and spin coating photoresist on the silicon wafer after the annealing treatment to obtain a silicon wafer coated with photoresist for the second time.

[0161] The annealing treatment is performed in the following manner: the sample with the magnetoresistance layer is placed into a small crucible, the crucible is horizontally placed into a glass tube with cotton balls plugged at both ends, vacuumizing is performed, the glass tube is sealed by using a glass column, the glass tube is placed into a constant-temperature furnace, the temperature rising speed is set to be 2 DEG C / min, the temperature holding temperature is set to be 350 DEG C, and the temperature holding time is set to be 3.5 h.

[0162] 5) performing second photoetching on the silicon wafer coated with photoresist for the second time to obtain a silicon wafer with external electrode patterns.

[0163] 6) performing thermal evaporation film plating on the silicon wafer with the external electrode patterns, and performing photoresist removing on the silicon wafer after the thermal evaporation film plating 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] The manufacturing method of the AMR sensor mainly comprises the technical content of any one of embodiments 11 to 12, and further, before spin coating the photoresist, the silicon wafer is further cleaned, and the cleaning method comprises an inert gas discharge plasma removing method and an acetone and isopropyl alcohol ultrasonic cleaning method.

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

[0168] Embodiment 13

[0169] The manufacturing method of the AMR sensor mainly comprises the technical content of any one of embodiments 11 to 12, and further, the photoresist is a mixture of polymethyl methacrylate and anisole.

[0170] The photoresist used in the photolithography is PMMA (Polymethyl Methacrylate). The PMMA powder is mixed with anisole to prepare a 5% mass fraction of PMMA photoresist.

[0171] Embodiment 14:

[0172] The method for manufacturing an AMR sensor, the main technical content of which is any one of embodiments 11 to 13, further, the pattern etched on the silicon wafer etched with the magnetoresistance strip and the shielding strip pattern includes four groups of magnetoresistance strips, a position marker pattern, two direction marker patterns, and four shielding strips.

[0173] The position marker pattern is located at the center of the silicon wafer, and two direction marker patterns are respectively arranged on the symmetric angles of the position marker pattern.

[0174] The position marker pattern and the direction marker pattern both present a cross shape.

[0175] The first group and the third group of magnetoresistance strips are arranged transversely, and the second group and the fourth group of magnetoresistance strips are arranged longitudinally, and are uniformly distributed around the position marker pattern.

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

[0177] Embodiment 15:

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

[0179] 2.1) Design the photolithography pattern of the magnetoresistance strip and the shielding strip in QCAD (open source plane design software).

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

[0181] 2.3) Develop the exposed silicon wafer to dissolve the photoresist at the place on the silicon wafer provided with the photolithography pattern.

[0182] The material used in the development includes methyl isobutyl ketone and isopropyl alcohol.

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

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

[0185] 5.2) Expose areas on the silicon wafer other than those with photolithographic patterns. Set the exposure dose to 180°C / cm. 2 The beam current is 3.2 nA and the amplification factor is 300.

[0186] 5.3) Develop the exposed silicon wafer to dissolve the photoresist on the silicon wafer where the photolithographic pattern is located.

[0187] The developer is a mixture of methyl isobutyl ketone (MIBK) and isopropanol in a 1:3 ratio. The development process consists of two steps: first, the exposed silicon wafer is placed in the developer at room temperature for 30 seconds, gently agitated to promote the dissolution of the photoresist; then, the wafer is immersed in isopropanol for 30 seconds to wash away the developer; finally, it is dried using a nitrogen gun.

[0188] Example 16:

[0189] A method for fabricating an AMR sensor, the main technical contents of which are described in any one of Examples 11 to 15, further, in step 5), when performing a second photolithography on the silicon wafer with secondary adhesive coating, the silicon wafer with secondary adhesive coating is aligned with the designed photolithographic pattern so that the external electrode is only connected to the corresponding magnetoresistive strip.

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

[0191] Example 17:

[0192] A method for fabricating an AMR sensor, the main technical contents of which are described in any one of Examples 11 to 16, further wherein the three-layer film structure of the sensing layer of the AMR sensor, from bottom to top, is Ta / Ni 80 Fe 20 / Ta, such as Figure 3 As shown, the bottom Ta layer is the seed layer, which is used for Ni. 80 Fe 20 Layer growth is promoted, and the top Ta layer acts as a protective layer to prevent Ni from growing. 80 Fe 20 The oxidation of the three layers is as follows: Ta 5nm, permalloy 11nm, and Ta 5nm.

[0193] Step 3), the step of obtaining a silicon wafer with a magnetron sputtered magnetoresistive layer includes:

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

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

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

[0197] 3.4) Open the sample shutter, sputter the silicon wafer with the pattern of magnetoresistive bar and shield bar to obtain the silicon wafer with seed layer.

[0198] 3.5) Turn off the RF power of Ta target and the sample shutter, turn on the RF power of the Permalloy target to pre-sputter.

[0199] 3.6) Open the sample shutter, sputter the silicon wafer with seed layer to obtain the silicon wafer with Ni 80 Fe 20 layer.

[0200] 3.7) Turn off the RF power of the Permalloy target and the sample shutter, turn on the RF power of Ta target to pre-sputter.

[0201] 3.8) Open the sample shutter, sputter the silicon wafer with Ni 80 Fe 20 layer to obtain the silicon wafer after magnetron sputtering.

[0202] 3.9) Remove the photoresist of the silicon wafer after magnetron sputtering to obtain the silicon wafer with magnetron sputtered magnetoresistive layer.

[0203] Example 18:

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

[0205] 3.9.1) Put the silicon wafer after magnetron sputtering into a container containing a photoresist removing solution, and blow gas on the edge of the silicon wafer with a dropper to obtain the silicon wafer after photoresist removing, and clean it with isopropyl alcohol.

[0206] The photoresist removing solution comprises acetone.

[0207] 3.9.2) Observe the silicon wafer after photoresist removing through a microscope to determine whether there is a part that has not been cleaned, if yes, go to step 3.9.3), if no, obtain the silicon wafer with magnetron sputtered magnetoresistive layer.

[0208] 3.9.3) Clean the silicon wafer after photoresist removing with appropriate ultrasonic cleaning, and return to step 3.9.2).

[0209] Example 19:

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

[0211] 6.1) Put the silver target and the chromium target into the evaporation boat of the evaporation device, and place the silicon wafer with the pattern of external electrode on the top of the inner cavity of the evaporation device.

[0212] 6.2) Vacuumize the inner cavity of the evaporation device.

[0213] 6.3) Turn on the target shutter and the chromium source power supply, and when the deposition is stable, turn on the sample shutter, and perform evaporation on the silicon wafer with the outer electrode pattern engraved thereon, and after the chromium layer is evaporated, turn off the sample shutter.

[0214] 6.4) Turn off the chromium source power supply, and turn on the silver source power supply, and when the deposition is stable, turn on the sample shutter, and perform evaporation on the silicon wafer with the chromium layer evaporated thereon, and after the silver layer is evaporated, turn off the sample shutter.

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

[0216] 6.6) Perform degumming on the silicon wafer after thermal evaporation film plating, to obtain the silicon wafer with the AMR electrode layer.

[0217] The step of performing degumming on the silicon wafer after thermal evaporation film plating is as follows:

[0218] 6.6.1) Place the silicon wafer after thermal evaporation film plating in a container containing degumming liquid, and blow gas on the edge of the silicon wafer with a dropper, to obtain the silicon wafer after degumming, and clean it with isopropyl alcohol.

[0219] The degumming liquid comprises acetone.

[0220] 6.6.2) Observe the silicon wafer after degumming through a microscope, to determine whether there is a part that is not cleaned, and if so, proceed to step 6.6.3), and if not, obtain the silicon wafer with the AMR electrode layer.

[0221] 6.6.3) Clean the silicon wafer after degumming with appropriate ultrasonic cleaning, and return to step 6.6.2).

[0222] Example 20:

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

[0224] 7.1) Manufacture a PCB sample holder.

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

[0226] 7.3) Connect the outer electrode in the silicon wafer with the AMR electrode layer and the pad of the PCB sample holder by means of indium wire pressure welding, and the steps are as follows:

[0227] 7.3.1) Melt the indium block with the tin bar and mix, get the melted alloy, then point the melted alloy on the external electrode of the silicon wafer.

[0228] 7.3.2) Stretch 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 on the external electrode in the silicon wafer with the AMR electrode layer and the male pad of the PCB sample holder respectively, and the pad and pin are connected through the wire on the PCB sample holder.

[0230] 7.4) Package the male holder of the PCB sample holder in an argon-filled environment using a packaging shell.

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

[0232] Example 21:

[0233] Referring to Figures 1 to 15 A method for manufacturing an AMR sensor, the main technical content of which includes:

[0234] The main process flow contained in the flow is:

[0235] (a) Clean the silicon wafer;

[0236] (b) Uniform glue (PMMA);

[0237] (c) Electron beam lithography (EBL);

[0238] (d) Magnetron sputtering of magnetic resistance layer (Ta / Fe / Ta);

[0239] (e) Degumming, vacuum annealing;

[0240] (f) Uniform glue (PMMA)

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

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

[0243] (i) Degumming;

[0244] (j) Indium wire pressure welding, packaging;

[0245] 1. The photoresist PMMA (Polymethyl Methacrylate) used in lithography. The PMMA powder is mixed with anisole to make a 5% mass fraction of PMMA photoresist. Plasma treatment is carried out before coating, using inert gas (argon) discharge plasma to remove impurities or contaminants on the surface of the substrate, and then using the method of spin coating, first low speed 500 rad / min for 2 s, then automatically change to 5000 rad / min for 50 s. The drawing designed in QCAD (open source flat design software) is imported into the control computer, and the running file of the photoetching machine is automatically generated after setting the parameters, and the exposure dose is set to 180 C / cm 2 , beam current is 3.2 nA, magnification is 300 times. There are two times of photoetching in total, and the parameters of the second photoetching are the same as the first one, so they are not described here.

[0246] Figure 2 is the design drawing of the first photoetching, in which the long strip (sharp corner, angle is 60°) is a magnetoresistance strip, and there are four groups of it, which are centrally symmetric. The shielding strip on the outermost of each group of magnetoresistance strips is used to reduce the magnetic field noise in space. The cross in the middle is used to align the two times of photoetching, and the large cross corrects the position and the small cross corrects the direction.

[0247] Developing. The developing solution is made by mixing methyl isobutyl ketone (MIBK) and isopropyl alcohol at a ratio of 1:3. Developing is divided into two steps. First, the exposed silicon wafer is placed in the developing solution at room temperature for 30 s, and can be gently shaken to promote the dissolution of the photoresist. Then the silicon wafer is soaked in isopropyl alcohol for 30 s to wash away the developing solution. Finally, the silicon wafer is blown dry with a nitrogen gun.

[0248] After the above steps, the first step of photoetching is completed, and whether the pattern meets the expected requirements and whether there is residual glue can be observed under an optical microscope.

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

[0250] The thicknesses of the three-layer film in this experiment are: Ta 5 nm, permalloy 11 nm, Ta 5 nm; The main steps of magnetron sputtering are: first, the equipment is vacuumed, first use the mechanical pump to 9e -1Pa then opens the molecular pump valve (the molecular pump is accelerated to 24000r / min first), and pumps to 1e -5 Pa; then argon is introduced, with a flow rate of 30sccm; the Ta target radio frequency power supply is turned on, with a direct current of 89mA and a voltage of 284V; pre-sputtering is performed for 3mins; then the sample shutter is opened, and sputtering is performed for 59s.

[0251] The radio frequency power supply of the Ta target and the sample shutter are turned off, the radio frequency power supply of the permalloy target is turned on, with a direct current of 76mA and a voltage of 399V; pre-sputtering is performed for 3mins, and then the sample shutter is opened, and sputtering is performed for 177s; the last layer of Ta is operated as above.

[0252] During the magnetron sputtering process, the excess metal is plated on the surface of the PMMA, at this time, the PMMA is dissolved using a solvent, and the metal film on the surface will fall off, the solvent used for degumming is acetone, and the method is as follows: the silicon wafer is placed in a container containing acetone, a dropper is used to continuously "blow air" at the edge of the silicon wafer (blow every 30min), and after 4h, the excess metal can be completely washed off, and the silicon wafer is placed under a microscope for inspection, and if there are parts that have not been cleaned, appropriate ultrasonic cleaning is used. The magnetoresistance layer after degumming is as shown in Figure 4 .

[0253] 3. Annealing treatment, the sample with the magnetoresistance layer is placed in a small crucible, the crucible is then placed horizontally in a glass tube with cotton balls at both ends, vacuum is drawn, and the glass column is used to seal the tube, and then the glass tube is placed in a constant temperature furnace, the temperature rising speed is set to 2℃ / min, the temperature holding temperature is 350℃, and the temperature holding time is 3.5h.

[0254] 4. The photoetching electrode layer of the second layer is basically the same as the first time, but the photoetching of the second layer is strictly required to be aligned with the pattern of the first layer, in order to achieve this purpose, the following method is adopted in this paper:

[0255] When designing the first layer, the mark points as shown in the following figure are left in the central part, by adjusting the position and direction of the large cross, the pattern can be accurately aligned.

[0256] Figure 5 The small crosses on both sides are used to mark the direction, Figure 6 the central alignment cross under 10000 times magnification of the electron microscope. By adjusting the position and direction, it is ensured that the two layers of patterns are accurately opposite to each other, as shown in Figure 7 .

[0257] 5. The AMR electrode layer is thermally evaporated and plated, silver and chromium targets are placed in the evaporation boat, and a silicon wafer is placed in the device, with the front side facing down and the back side adhering to the tray, and placed above the internal cavity of the device; vacuum is drawn, first the mechanical pump is opened, and the gas pressure in the cabin is pumped to 1e-1 P< 1000C, then turn on the power of the molecular pump, when the molecular pump speed reaches 24000r / min, open the molecular pump valve, until the vacuum degree of the device reaches 5x10-6Torr, open and run, chromium as seed layer, evaporation 5nm, open the target baffle, turn on the chromium source power, set the current to 160A, when the panel shows deposition, open the sample baffle, click the sample rotation button and set the thickness to zero, the instrument automatically monitors the thickness, when the thickness shows 5nm, close the sample baffle and stop the sample rotation, turn off the chromium source, and close the chromium source baffle. Silver plating 40nm, open the target baffle, turn on the silver source power, set the current to 60A, when the panel shows deposition, open the sample baffle, click the sample rotation button and set the thickness to zero, the instrument automatically monitors the thickness, when the thickness shows 40nm, close the sample baffle and stop the sample rotation, turn off the silver source, and close the silver source baffle. After completion, remove the silicon wafer and pump out the air in the device. Excess metal will be plated on the surface of PMMA during magnetron sputtering. At this time, the PMMA is dissolved using a solvent, and the surface metal film will fall off. The solvent used for degumming is acetone, and the method is as follows: introduce sufficient acetone into the container, immerse the silicon wafer completely in it, seal the container opening with plastic film to prevent acetone evaporation, and stand for a period of time. When the metal film surface peels off and becomes uneven, gently shake the container to make the metal film peel off. When the metal is difficult to peel off, consider using ultrasonic equipment to complete the peeling. After degumming, the results are as shown in Figure 8

[0258] 6Indium wire pressure welding, packaging. The packaged device is composed of a shell, a PCB sample holder, and an indium connecting line. The PCB sample holder is designed as a pluggable structure composed of a male holder and a female holder (the male holder is soldered with pins, and the female holder is soldered with a jack connected to an external circuit). The indium connecting line can connect the sample with AMR to the pads of the PCB sample holder, and then to the pins. Figure 9 In order, a) PCB sample holder male holder; b) PCB sample holder female holder, c) AMR sensor after pressure welding, d) AMR sensor placed on the ground base.

[0259] The PCB drawn in Altium Designer is shown in Figure 10

[0260] Indium pressure connection: the prepared chip is glued to the reserved position on the PCB, and at this time the external electrode in the sample with AMR is connected to the pads of the PCB sample holder by indium wire pressure welding.

[0261] The indium pressure process is as follows:

[0262] ​​1) A small amount of indium block is mixed with tin bar after melting with a soldering gun, then the melted alloy is dotted on the electrode around the chip with the soldering gun;

[0263] 2) A small amount of indium block is melted with a soldering gun and kept in a molten state, a section of enameled wire is inserted into the liquid indium, and an indium wire is slowly pulled out, requiring a thin head and a thick body, and a suitable length;

[0264] 3) The ends of the indium wire are pressed on the lead electrodes of the chip and the pads of the PCB under a microscope;

[0265] Assembly: The public holder is packaged in an argon-filled glove box to avoid the influence of air components on the resistance part of the magnetic sensing element, thereby affecting the performance of the magnetic sensing element. The packaging shell is divided into two parts, a fence and a cover plate. The fence is made of 3D printing, and the cover plate is a quartz plate, as shown in Figures 11-12 .

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

[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 shown in Figure 14 , the external magnetic field is perpendicular to the direction of the four magnetic resistance strips upward. R1 = R4 = R + ΔR, R2 = R3 = R - ΔR.

[0269] Output:

[0270] The design simplifies the traditional AMR sensor manufacturing process, and due to the higher precision of electron beam lithography, the size of the AMR sensor is also relatively reduced, with the widest part being only 1mm.

[0271] The output performance of the AMR sensor of the design is shown in Figure 15 .

[0272] The sensitivity is 0.109mV / V / Oe, and the maximum accuracy is 0.033Oe.

Claims

1. A method of fabricating an AMR sensor, the method comprising: The method comprises the following steps: 1) spin coating photoresist on the surface of a silicon wafer; 2) performing first photoetching on the silicon wafer coated with the photoresist to obtain a silicon wafer with magnetoresistance strips and shielding strips, the step comprising: 2.1) designing a photoetching pattern of the magnetoresistance strips and the shielding strips; 2.2) exposing the silicon wafer except the part provided with the photoetching pattern; 2.3) developing the exposed silicon wafer; The material used in the developing comprises methyl isobutyl ketone and isopropyl alcohol; The pattern etched on the silicon wafer with the magnetoresistance strips and the shielding strips comprises four groups of magnetoresistance strips, a position marker pattern, two direction marker patterns and four shielding strips; The position marker pattern is located at the center of the silicon wafer, and two direction marker patterns are respectively arranged at the symmetric angles of the position marker pattern; The first group and the third group of magnetoresistance strips are arranged horizontally, and the second group and the fourth group of magnetoresistance strips are arranged vertically and uniformly distributed around the position marker pattern; The four groups of magnetoresistance strips are symmetrically distributed at the center, and the outermost side of each group of magnetoresistance strips is a shielding strip; 3) performing magnetron sputtering on the silicon wafer with the magnetoresistance strips and the shielding strips, and performing photoresist removing on the silicon wafer after the magnetron sputtering to obtain a silicon wafer with a magnetron sputtering magnetoresistance layer, the step comprising: 3.1) vacuumizing the operation chamber of an operation device; 3.2) introducing argon into the operation chamber of the operation device; 3.3) starting a Ta target radio frequency power supply to perform pre-sputtering; 3.4) opening a sample shutter to perform sputtering on the silicon wafer with the magnetoresistance strips and the shielding strips to obtain a silicon wafer with a seed layer; 3.5) closing the Ta target radio frequency power supply and the sample shutter, and starting a permalloy target radio frequency power supply to perform pre-sputtering; 3.6) Open the sample shutter and sputter the silicon wafer with seed layer to obtain a silicon wafer with a layer of Ni 80 Fe 20 layer. 3.7) closing the permalloy target radio frequency power supply and the sample shutter, and starting the Ta target radio frequency power supply to perform pre-sputtering; 3.8) Open the sample shutter, sputter the silicon wafer with Ni 80 Fe 20 layers, and obtain the magnetron-sputtered silicon wafer; 3.9) performing photoresist removing on the silicon wafer after the magnetron sputtering to obtain the silicon wafer with the magnetron sputtering magnetoresistance layer; 4) performing annealing treatment on the silicon wafer with the magnetron sputtering magnetoresistance layer, and spin coating photoresist on the silicon wafer after the annealing treatment to obtain a silicon wafer with secondary photoresist; 5) performing second photoetching on the silicon wafer with the secondary photoresist to obtain a silicon wafer with an external electrode pattern, the step comprising: 5.1) designing a photoetching pattern of the external electrode; 5.2) exposing the silicon wafer except the part provided with the photoetching pattern; 5.3) developing the exposed silicon wafer; When performing the second photoetching on the silicon wafer with the secondary photoresist, the silicon wafer with the secondary photoresist is aligned with the designed photoetching pattern, so that the external electrode only communicates with the corresponding magnetoresistance strip; 6) performing thermal evaporation plating on the silicon wafer with the external electrode pattern, and performing photoresist removing on the silicon wafer after the thermal evaporation plating 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 of claim 1, wherein the AMR sensor is fabricated by a process comprising: In step 1), before spin coating the photoresist, the silicon wafer is also cleaned, and the cleaning method comprises an inert gas discharge plasma removing method and an acetone and isopropyl alcohol ultrasonic cleaning method.

3. The method of claim 1, wherein the AMR sensor is formed by a process comprising: The photoresist is a mixture of polymethyl methacrylate and anisole.

4. The method of claim 1, wherein the AMR sensor is fabricated by a process comprising: In step 3.9), the step of performing photoresist removing on the silicon wafer after the magnetron sputtering comprises: 3.9.1) placing the silicon wafer after the magnetron sputtering in a container containing a photoresist removing solution, and blowing gas at the edge of the silicon wafer with a dropper to obtain the silicon wafer after the photoresist removing; The degumming solution comprises acetone; 3.9.2) observing the silicon wafer after degumming through a microscope to determine whether there are parts that have not been cleaned, if so, going to step 3.9.3), if not, obtaining the silicon wafer with the magnetron sputtering magnetic resistance layer; 3.9.3) using ultrasonic cleaning to clean the silicon wafer after degumming, and returning to step 3.9.2).

5. The method of claim 1, wherein the AMR sensor is fabricated by a process comprising: In step 6), the step of obtaining the silicon wafer with the AMR electrode layer comprises: 6.1) placing the silver target and the chromium target into the evaporation boat of the evaporation device, and placing the silicon wafer with the external electrode pattern on the top of the inner cavity of the evaporation device; 6.2) vacuumizing the inner cavity of the evaporation device; 6.3) opening the target shutter and the chromium source power supply, when the deposition is stable, opening the sample shutter, and performing evaporation on the silicon wafer with the external electrode pattern, after the evaporation of the chromium layer is completed, closing the sample shutter; 6.4) closing the chromium source power supply, opening the silver source power supply, when the deposition is stable, opening the sample shutter, and performing evaporation on the silicon wafer with the chromium layer, after the evaporation of the silver layer is completed, closing the sample shutter; 6.5) closing the target shutter and the silver source power supply, and taking out the silicon wafer with the chromium layer and the silver layer, to obtain the silicon wafer after thermal evaporation plating; 6.6) degumming the silicon wafer after thermal evaporation plating to obtain the silicon wafer with the AMR electrode layer; The step of degumming the silicon wafer after thermal evaporation plating comprises: 6.6.1) placing the silicon wafer after thermal evaporation plating into a container containing a degumming solution, and blowing gas on the edge of the silicon wafer with a dropper to obtain the silicon wafer after degumming; The degumming solution comprises acetone; 6.6.2) observing the silicon wafer after degumming through a microscope to determine whether there are parts that have not been cleaned, if so, going to step 6.6.3), if not, obtaining the silicon wafer with the AMR electrode layer; 6.6.3) using ultrasonic cleaning to clean the silicon wafer after degumming, and returning to step 6.6.2).

6. The method of claim 1, wherein, In step 7), the step of obtaining the AMR sensor comprises: 7.1) making a PCB sample holder; 7.2) gluing the silicon wafer with the AMR electrode layer into the PCB sample holder; 7.3) using indium wire pressure welding to connect the external electrode in the silicon wafer with the AMR electrode layer and the pad of the PCB sample holder, which comprises the following steps: 7.3.1) melting the indium block and the tin bar with a soldering gun, mixing them, obtaining the molten alloy, and then dropping the molten alloy on the external electrode of the silicon wafer; 7.3.2) inserting the enameled wire into the liquid indium, and pulling out an indium wire; 7.3.3) pressing the two ends of the indium wire on 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 holder of the PCB sample holder in an argon-filled environment; The packaging shell comprises a fence and a cover plate.

Images