Evaluation of resonating Si cantilevers sputter-deposited with AlN piezoelectric thin films for mass sensing applications

Abstract

We report on a micro-machined resonator for mass sensing applications which is based on a silicon cantilever excited with a sputter-deposited piezoelectric aluminium nitride (AlN) thin film actuator. An inductively coupled plasma (ICP) cryogenic dry etching process was applied for the micro-machining of the silicon substrate. A shift in resonance frequency was observed, which was proportional to a mass deposited in an e-beam evaporation process on top. We had a mass sensing limit of 5.2 ng. The measurements from the cantilevers of the two arrays revealed a quality factor of 155–298 and a mass sensitivity of 120.34 ng Hz−1 for the first array, and a quality factor of 130–137 and a mass sensitivity of 104.38 ng Hz−1 for the second array. Furthermore, we managed to fabricate silicon cantilevers, which can be improved for the detection in the picogram range due to a reduction of the geometrical dimensions.