Biaxial film bulk acoustic resonator magnetic sensor based on the Fe80Ga20 anisotropic ΔE effect

Abstract

With the increasing application of personal navigation systems in consumer electronics, the demand for multi-axis magnetic sensors based on MEMS is growing. We report a biaxial MEMS DC magnetic sensor consisting of an Mo/AlN/Fe80Ga20 film bulk acoustic resonator, with anisotropy ΔE effect-based sensing principle. Different from the previously reported 1D magnetic sensor based on the ΔE effect, the anisotropic ΔE effect was used to realize in-plane and out-of-plane 2D magnetic field responses on a discrete sensor, and the sensor had two readout methods: resonant frequency f and return loss S11. The magnetic sensor realized the resonant frequency f shifted by 1.03 MHz and 0.2 MHz in the 567 Oe in-plane magnetic field and 720 Oe out-of-plane magnetic field, respectively, and the S11 changes by −30.2 dB and −0.92 dB. As the applied magnetic field increases, the −3 dB bandwidth quality factor Q 3dB of the S11 curve gradually increases, and its maximum values in the in-plane and out-of-plane magnetic fields are 77 143 and 1828, respectively, which reduces the detection limit of the magnetic sensor. The resonant magnetic sensor has stable high linear temperature and frequency drift characteristics, and its temperature frequency coefficient is −48.7 ppm °C−1.