Low-Vacuum Sensing With Silicon-On-Nothing Resonating Membrane

This paper presents a novel piezoelectric over silicon-on-nothing (PSON) membrane resonator for highly sensitive low-vacuum detection. Conventional piezoresistive sensors, primarily designed for positive pressure sensing, face limitations in vacuum applications due to assembly-induced stress, temperature variations, and outgassing errors. The proposed device addresses these challenges by integrating a piezoelectric Sc-doped AlN film on a silicon membrane suspended over a vacuum cavity. The frequency response of the membrane was characterized across a pressure range from atmospheric pressure down to 69.35 mbar, under varying DC bias conditions. Results show that applying a -40 V DC bias enhances sensitivity, with a frequency shift of -61 Hz/mbar (-64.1 ppm/mbar), due to increased membrane compressive relaxation. This PSON-based sensor demonstrates superior accuracy, miniaturization potential, and robustness for low-vacuum applications, making it a promising alternative for industries such as semiconductor manufacturing, aviation, and medical devices.