Mechanical robust biaxial MEMS mirror achieving > 100° optical scanning angle for LiDAR application

MEMS micromirrors typically require the use of elongated torsion beams to achieve optical scanning angles in excess of 90°, but elongated torsion beam structures usually lead to problems such as larger chip areas and lower reliability. This paper designs a biaxial Lissajous scanning piezoelectric AlScN-driven MEMS micromirror driven by circular arc actuators, featuring large mirror with a diameter of 5 mm. To achieve large-angle scanning, optimizations are made in the following four aspects: 1) stress dispersion structures are adopted in the structural design; 2) an improved non-Bosch process is utilized in the manufacturing process to achieve smooth sidewall morphology; 3) vacuum packaging is employed in the packaging aspect to reduce the impact of air damping; 4) a driving method of gradually reaching the resonance peak through upward frequency sweeping is used in the control aspect, fully exploit the spring hardening effect to achieve large-angle scanning. After optimization, the mirror achieves optical scanning angles of 102.8° and 104.8° on its two axes. Furthermore, the micromirror has passed 900g shock tests and 20g vibration tests, demonstrating its good shock and vibration resistance while achieving large scanning angles.