A test structure to inform the effects of dielectric charging on CMOS MEMS inertial sensors

Reducing drift in MEMS devices (e.g. resonators, inertial sensors) is a crucial component of performance. As electrostatic modes of sense and actuation are frequently employed in these devices, charging in dielectric materials is an important consideration. In CMOS MEMS technologies where electrostatic spring softening effects are present, drift due to charging can be significant, effectively overwhelming the device´s ability to sense or be actuated. In this paper, we characterize the response of a test structure to various bias conditions to aid in modeling of device charging in inertial sensors. A preliminary model is presented to predict the bias state of the device due to dielectric charging.