Microfabrication of piezoelectric MEMS based on thick LiNbO₃ single-crystal films

Abstract

Microfabrication procedure of piezoelectric micro electro-mechanical systems based on 5 µm thick LiNbO3 films on SiO2/Si substrate at wafer scale including deep dry etching of thick LiNbO3 films by implementing pulsed mode of Ar/SF6 gas was developed. In particular, two (YXlt)/128°/90°LiNbO3-Si cantilevers with tip mass were fabricated and characterized in terms of resonance frequency (511 Hz and 817 Hz), actuation and acceleration sensing capabilities. The quality factor of 89.5 and the electromechanical coupling of 4.8 % were estimated from measured frequency dependency of electrical impedance, fitted by using BVD model. The fabricated piezoelectric MEMS have demonstrated highly linear displacement with good sensitivity (5.28±0.02 µm/V) as a function of applied voltage and high sensitivity to vibrations of 667 mV/g indicating a suitability of the structure for actuation purposes and for acceleration or frequency sensing with high precision, respectively.