Self-assembled silicon membrane resonator for high vacuum pressure sensing

Abstract

In this paper, a mechanical vacuum gauge based on a circular membrane resonator is proposed and its high responsivity is verified in high vacuum down to a pressure of ∼6 × 10−7 mbar. A silicon-on-nothing (SON) resonator with a self-sealed cavity having a diameter of 150μm and a thickness of 1.55μm is fabricated through a high vacuum annealing process. After the fabricated membrane resonator is placed inside a custom vacuum chamber, its resonant characteristics are measured with a frequency sweep, and the vibration amplitudes are measured by resonance feedback using a laser and photodiodes at various vacuum pressures. Using quality factor (Q factor) measurement, the SON resonator shows a high responsivity (ΔQ/ΔP) of up to ∼3.7 × 108 mbar−1 in the high vacuum range. Both quality factor and amplitude are found to be effective vacuum indicators, and amplitude measurement is specifically useful for real-time vacuum monitoring.