A STUDY OF SILICON ANGULAR RATE SENSORS USING ANISOTROPIC ETCHING TECHNOLOGY

Silicon angular rate sensors are studied. The structure and fabricatio n process are quite simple and mass-producible. The silicon rate senso rs have an oscillation bar and detection electrodes on a glass base. T he oscillation bar and the detection electrodes are simultaneously for med by a silicon anisotropic etching process. The oscillation bar is v ibrated at its resonance frequency by a piezo-actuator. The applied an gular rate generates the Coriolis' force to the oscillation bar, and t he oscillation bar deviates from its normal orbit of the vibration. Th is deviation makes the capacitance change between the oscillation bar and the detection electrodes. The cappicitance change is converted int o the voltage level which is the output voltage of the sensor. The tes t device shows a sensitivity of about 20 mV/(rad/s) and a linearity of 2% FS (full scale). The resolution (or equivalent noise level) is now 0.1 rad/s. In this paper, the fabrication process and the measured da ta of the test device are presented. Moreover, the improved structure with respect to the acceleration sensitivity is discussed.