Si-to-Si fusion bonded touch mode capacitive pressure sensors

Touch mode capacitive pressure sensors are shown to have better performance in industrial applications than other devices. The advantages include good linearity in the operating range, mechanical roughness and large overload protection. In the design and fabrication of micro sensors and actuators, the understanding of deflection, stress and strain of thin diaphragms with clamped edges under various load conditions, including when the diaphragm touches the substrate, is of great importance, but a complex design issue. This article reports the finite element modeling (FEM) of these diaphragms, design and fabrication of a touch mode capacitive pressure sensor using silicon fusion bonding technology. By geometrically nonlinear computing and using GAP element in ABAQUS, the deflection, stress and strain of a diaphragm in touch mode can be calculated. The simulation results can be used to predict the sensor's performance, thus served as a computer aided design tool to determine sensor's parameters in industrial applications. Using silicon fusion bonding technology, an all-single crystal silicon capacitive have been fabricated and evaluated. (C) 1998 Elsevier Science Ltd. All rights reserved.