Concepts and limits for the miniaturization of silicon differential vibrating inertial micro-beam accelerometer

In this paper, an original differential VBA: the ISA-100 structure including an isolating system is presented in order to explore the fundamentals parameters for the miniaturization of such devices (4 to 1 mum thick beam). The bias stability of the sensor depends directly on the frequency stability of each beam, and thus requires a high quality factor Q. Q values up to 2.4 times 10⁵ have been measured for 3 mum thick resonators. But high Q values are an advantage up to a certain extent. Indeed as the sensitive element gets thinner and Q values get higher, resonators are more susceptible to nonlinear effects. Experiments have revealed a nonlinear behaviour for a deflection lower than 10 nanometers. The influence of the Q-factor on the nonlinear behaviour of the VBA and then on its resolution (noise level) and frequency stability is studied.