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

MEMS mirrors often face issues such as silicon material fracture during large-angle scanning. For MEMS devices with larger mirror sizes, due to the influence of air damping, the voltage amplitude is usually insufficient to drive the micromirror for large-angle scanning. 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 three aspects. 1) In order to reduce the risk of silicon material fracture during large-angle scanning, stress dispersion structures are adopted in the structural design, and an improved non-Bosch process is utilized in the manufacturing process to achieve smooth sidewall morphology. 2) For achieving large-angle scanning of the large-size mirror at a lower voltage amplitude, vacuum packaging is employed in the packaging to reduce air damping. 3) To find the resonant frequency under nonlinear effects, we utilize a frequency-sweeping driving method to actuate the MEMS mirror. After optimization, the mirror achieves total optical scanning angles of 102.8° and 104.8° on its two axes. Furthermore, the mirror has passed 900g shock tests and 20g vibration tests, demonstrating its good shock and vibration resistance while achieving large scanning angles.