基于电容检测MEMS磁传感器的设计与制作

为实现微型化、低功耗、低成本和高灵敏度的磁传感器，提出了一种基于微型磁扭摆结构的磁传感器，并利用对角度变化非常敏感的差分电容检测技术对磁扭摆的扭转角度进行检测．设计的磁传感器包括微扭摆结构、磁性敏感薄膜和差分检测电容等部分．分析了器件的磁敏感原理和电容检测原理，给出了器件的结构参数和综合设计考虑．利用体硅加工工艺成功制作出了磁传感器样品，并进行了实验测试．测试结果表明磁传感器有良好的线性度和重复性，其磁场检测的电容灵敏度可达到0．2fF／Gauss．根据对磁传感器的热噪声分析，可得到磁传感器最小可分辨的磁场为6．72μT．该磁传感器结构简凑、工艺简单，无需电流激励，大大降低了磁传感器功耗．

Design and Fabrication of MEMS Magnetic Sensor Based on Capacitance Detection

In order to achieve micromation, low power consumption, low cost and high sensitivity of mag- netic sense, a new micro magnetic field sensor based on torsion pendulum mechanism was presented in this paper. Differential capacitance detection was used for measuring the tiny angle variation of torsional pendulum. The magnetic sensor consisted of micro torsional pendulum, magnetic film and differential ca- pacitance. Mechanisms of magnetic sensing and capacitance detection of the device were described, and basic design and analytical optimization of the device were discussed. The magnetic sensor was fabricated using bulk micro-mechanical technology. Experimental resuhs indicate the good linearity and repeatability of the sensor. The capacitive sensitivity of magnetic field detection turns out to be 0. 2 IF/Gauss. The magnetic resolution of the sensor is calculated to be 6.72 μT by using thermal noise analysis. The mag- netic sensor has the advantages of structural simplicity and compactness, easy fabrication, and no current excitation, which will reduce power consumption significantly.