Fatigue Analysis and Estimation of the Number of Exposure Cycles until the Failure of the Sensitive Element of a Micromechanical Capacitive Accelerometer

Abstract

Ensuring the reliability of the functioning of MEMS devices is the most important task facing developers. Due to the variety of designs and materials used in MEMS devices, various failure mechanisms can occur. Most of these devices contain moving parts of the structure. The fatigue properties of the structural materials used and their aging under prolonged repetitive cyclic loading can lead to failure, which directly affects the reliability of the device. In this paper the fatigue properties and reliability of the sensitive element (SE) of a micromechanical accelerometer (MMA) sandwich structure of a capacitive type made of silicon under the conditions of the mechanism of fatigue failure of the material are analyzed. The number of cycles of periodic exposure for the occurrence of a failure and the failure rate of SEs are calculated. The crystallographic orientation of the surface plane of silicon—the SE material—is considered. The simulation results show that the fatigue life of SE of an MMA made of silicon can be sufficiently strong for general purpose applications.