Моделирование и исследование различных типов подвесов инерционной массы в чувствительных элементах микромеханических приборов

Abstract

In microelectromechanical devices and systems (MEMS), capacitive micromechanical accelerometers (MMA) are used in airbag systems, machine vibration monitoring, navigation, seismology, microgravity measurements, etc. The most important structural elements of the sensing element are suspensions, through which the inertial mass is connected to a fixed frame. To ensure reliable operation and stability of sensor parameters, it is necessary to take into account the results of external factors already at the design stage of the sensor structure, especially its sensitive element, and at subsequent stages of the life cycle. In this work, the characteristic structures of suspension elements, which are made of silicon with different crystallographic orientations, are investigated and the results of modeling their most important parameters are presented. The simulation has been performed using the ANSYS program. The natural frequencies of inertial mass oscillations, residual mechanical stresses in the structural elements of silicon sensitive element with different crystallographic orientations have been calculated upon impact (up to 10 000 g). The natural vibration frequency changes and the dynamics of the change in the residual mechanical stress in the suspension elements with a temperature change in the range from +150 to –150 °C for a short time interval of 10 s, which corresponds to thermal shock, investigated. The results of studies of residual mechanical stresses arising upon impact and natural frequencies of inertial mass oscillations have been made it possible to develop recommendations on the choice of the design of suspension elements made of silicon, providing high sensitivity and stability of MMA parameters. It has been established that the use of folded springs with a rectangular or round cross-sectional shape with a suspension element thickness of 40 μm provides the highest temperature stability of the parameters. The results obtained are useful for developing real designs of MMA and other micromechanical devices