Research On 3D Magnetic Field Sensor Based On MEMS Technology

Aiming at the practical application requirements of 3D magnetic field sensor for nondestructive testing in industry and solve the problem of single magnetic sensitive direction of Hall element.In this paper,a 3D magnetic field sensor is designed based on MEMS technology,combining Hall element and conducting magnetic flux structure,the sensor includes five Hall elements(H-1,H-2,H-3,H-4 and H-5)and four CMFS(CMFS1,CMFS2,CMFS3 and CMFS4),and consists of three magnetic sensitive units,completed the detection of the external magnetic field component(B_x,B_y and B_z).To realize the detection of space magnetic field vector,CMFS is embedded in the deep groove structure directly below the sensitive area of four Hall elements of x-and y-axis magnetic sensing unit.Its function is to modulate the horizontal magnetic field relative to the sensitive area of element to the vertical direction,so that Hall element can detect the applying magnetic field along non-sensitive axis.On these basis,a simulation model of the CMFS of 2D magnetic field was constructed and the conducting characteristics of CMFS were simulated by using finite element software ANSYS Workbench;the magnetic sensitivities of sensitive units along x-,y-,and z-axis were simulated by TCAD-Atlas.L-edit software was used to complete the layout design of the 3D magnetic field sensor chip,based on MEMS technology to complete the chip fabrication on SOI wafer,and inner-wire bonding technology was used to realize the package of the sensor chip.Under room temperature,a self-built testing platform was used to test and analyze the magnetic sensitivities along x-,y-and z-axis,cross interference of magnetic sensitivities and temperature characteristics of the 3D magnetic field sensor.Experimental results showed that when the applied magnetic field is-20 m T?20 m T,the magnetic sensitivities of the sensor along x-,y-,and z-axis were 351.6 m V/T,331.9m V/T and 112.6 m V/T,respectively.After fabricating magnetic shielding layer on the side of CMFSs;the sensitivities along x-and y-axis were 325.6 m V/T and 321.0 m V/T,respectively.This 3D magnetic field sensor used CMFSs to modulate the direction of the applying magnetic field,the same kind of Hall elements can realize 3D magnetic field measurement,which lays the foundation for the research of high-performance space magnetic field vector sensor.