基于聚磁结构磁场传感器特性研究

Characteristics research of magnetic filed sensor based on collecting magnetic field structure

给出由硅磁敏三极管和两个聚磁结构构成的磁场传感器。聚磁结构为镍铁合金材料制作的梯形结构,可放大外加磁场,硅磁敏三极管能够实现外加磁场测量,聚磁结构改善了磁场传感器磁灵敏度特性。利用ANSYS有限元软件构建了聚磁结构仿真模型,研究了结构尺寸对聚磁性能的影响,在此基础上采用电火花技术制作了聚磁结构,同时采用MEMS技术在p型高阻单晶硅上设计、制作了磁敏三极管芯片,利用微电子封装工艺实现了磁敏三极管和聚磁结构的无磁化封装。当电源电压V DD=5.0 V、集电极负载电阻R L=2.3 kΩ、基极注入电流I b=8.0 mA时,在室温下且磁场范围为-80 mT^+80 mT,基于聚磁结构磁敏三极管磁灵敏度为926 mV/T。实验结果表明,聚磁结构提高了磁灵敏度约3.5倍。

A magnetic field sensor is proposed in this paper,consisting of a silicon magnetic sensitive transistor(SMST)and two collecting magnetic field structures(CMFSs)fabricated based on Ni-Fe alloy material by using wire cut electrical discharge machining(WEDM)technology.Using finite element software ANSYS to analyze the properties of the CMFS achieved the optimization of the sensor structure by adjusting the dimensions and angles.Based on that,the sensor chip was designed and fabricated on a p-type silicon wafer with a high resistivity utilizing microelectromechanical system(MEMS)technology.The experimental results show that in the conditions of supply voltage V DD=5.0 V,the collector load resistance R L=2.3 kΩand the base injection current I b=8.0 mA,the proposed SMST with a CMFS represents an excellent sensitivity of 926.1 mV/T about 3.5 times than that without the one in a magnetic field range from-80 mT to+80 mT at room temperature.The study on the magnetic field sensor with a CMFS makes it possible to improve the magnetic sensitivity of the SMST and achieve a high amplification.