AMR Linear Magnetoresistive Sensor Optimization

AMR(Anisotropic Magnetoresistive)linear magnetoresistive sensor is a magnetic field sensor that utilizes the AMR effect.Today,Thanks to the development of microelectronics technology,especially the development of thin-film technology.anisotropic magnetoresistive sensors have the advantages of high detection sensitivity,high temperature stability and low price compared with other sensors based on semiconductor Hall effect or giant magnetoresistive effect.The price is especially suitable for large market occasions.At present,the mainstream AMR magnetic field sensors are mainly produced abroad,and there are no large-scale commercial products in China.This paper obtains a high-performance magnetic field sensor by optimizing AMR linear magnetoresistive sensor based on the Barber electrode.First,through the electromagnetic finite element model,the current and magnetic field distribution of the AMR sensor unit biased by different Barber electrode angles and spacings were simulated.First,the partial differential equation solution software Fenics was used to simulate.When the magnetic moment in the magnetoresistive layer rotates 180 °,the current output at both ends of the sensing unit changes.It was found that when the fixed electrode spacing at 10 μm,the electrode angle was changed from 30 ° to 60 °,with a size point every 5 °.The device has a relatively good linearity of 0.5% and 0.8% at 40 ° and 55 °,respectively.When the fixed electrode angle is 45 ° and the electrode spacing is changed from 10μm to 22μm,every 2μm is a size point.The results show that when the electrode spacing is 10 μm and 12 μm,there is relatively good linearity of 1% and 1.2% respectively.Then,the finite element numerical simulation software COMSOL Multiphysics was used to simulate the current density distribution,current angle distribution,and self-bias field of the device.It is found that the uniform current density is mainly distributed in the device size points where the electrode angle is above 50 ° and the electrode spacing is above 16μm,The area where the current deflection angle is close to 45 ° is below the electrode angle of 40 ° and the area between the electrode spacing is below 16μm.Therefore,it can be expected that the output characteristics of the device do not change monotonously with the geometry.Then,the self-bias magnetic field in the magnetoresistive layer of the device is simulated.It is found that the maximum transverse magnetic field reaches 0.7 Oe / mA.For devices with a magnetic field size of ± 6Oe in the working interval,this will affect the use of the device.However,when the electrode angle is less than 45 ° and the electrode spacing is less than 12μm,the lateral self-bias magnetic field is relatively small,about 0.1 Oe / mA.To study the actual performance of the device with various size point combinations,a wafer-level array layout design was made for the sensor pattern,and the preparation process was studied.It was found that when preparing the Barber electrode layer,the etching and corrosion processes are difficult Complete device pattern at the wafer level.Finally,the device with the design size error within 5% was prepared under the stripping process.Finally,some of the fabricated sensors were tested.When the electrode spacing was 12 μm,the electrode angles were 40 °,45 °,50 °,and 55 °.When the electrode angle was 60 °,the electrode spacing was 10 μm.,12μm,14μm,16μm device.According to the test results,it is found that the device-dependent parameters(linearity,sensitivity,self-bias magnetic field)depend on the electrode angle more than the electrode spacing.And consistent with the simulation results is that the device has the best sensitivity of 0.074 mV / V / Oe and linearity of 1.1% when the electrode spacing is 12μm and the electrode angle is 40 °.And the linear magnetoresistive sensor we made is better than the similar foreign product HMC1022 in linearity.