DESIGN AND CHARACTERIZATION OF AN ALN PIEZOELECTRIC MEMS MAGNETOMETER

This work presents an in-house design, fabrication, and characterization of a resonant piezoelectric MEMS device using the Thin-film Piezoelectric-on-Silicon (TPoS) process of AlN to realize a Lorentz force-based magnetic sensor. The magnetometer is designed by employing the flapping-mode of the rectangular resonator fixed at the center of the two opposite edges. The resonator is characterized by Laser Doppler Vibrometer and electrical measurements which show a resonance frequency of 356 kHz with Q of 767 in air. The output voltage of the magnetometer shows a linear increase with magnetic field strength indicating sensitivity and responsivity of 79.28 mV/T and 2128 ppm/T respectively. The frequency response of the device also shows a phase inversion upon reversing the direction of the magnetic field. The measured instability in the magnetic field was 0.283 mu T extracted from Allan deviation, to the best our knowledge the lowest value among state-of-the-art AlN MEMS magnetometers.