A STUDY OF SILICON ANGULAR RATE SENSORS USING ANISOTROPIC ETCHING TECHNOLOGY

Silicon angular rate sensors are studied. The structure and fabrication process are quite simple and mass-producible. The silicon rate sensors have an oscillation bar and detection electrodes on a glass base. The oscillation bar and the detection electrodes are simultaneously formed by a silicon anisotropic etching process. The oscillation bar is vibrated at its resonance frequency by a piezo-actuator. The applied angular rate generates the Coriolis' force to the oscillation bar, and the oscillation bar deviates from its normal orbit of the vibration. This deviation makes the capacitance change between the oscillation bar and the detection electrodes. The cappicitance change is converted into the voltage level which is the output voltage of the sensor. The test 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 data of the test device are presented. Moreover, the improved structure with respect to the acceleration sensitivity is discussed.