Chipping and wearing in MEMS inertial sensors: effects on stability and predictive analysis through test structures

Impacts between fixed and moving parts in capacitive MEMS inertial sensors can generate debris and wear that undermine the device stability. This work investigates the effects of impacts and friction between rotors and stoppers through dedicated test structures. After modeling the scenario, considering the impact kinetic energy and the tensile/ compressive nominal strength of silicon, different stopper topologies and collision angles are studied. Results show how impact kinetic energies, up to 40 nJ (velocities in the 1-3 m/s range for typical inertial sensor masses), correlate with silicon rupture and provide first guidelines for robust sensors design.