AlScN Thin Films for the Piezoelectric Transduction of Suspended Microchannel Resonators

Suspended microchannel resonators (SMRs) are powerful tools for mass, density, and viscosity sensing. Among various transduction methods, full piezoelectric transduction offers key advantages, including on-chip integration, low energy dissipation, and linear response. This work explores sub-200 nm Al_0.6Sc_0.4N thin films for SMR transduction, benchmarking them against their well-established AlN predecessor. By integrating the piezoelectric stack into low-stress silicon nitride (ls-SiN_x) beam resonators, we investigate the impact of bottom electrode design, photoresist removal prior to deposition, and deposition bias on film quality. Characterization includes X-ray diffraction (XRD), scanning electron microscopy (SEM), d₃₁ piezoelectric coefficient, relative dielectric permittivity, and breakdown field measurements. Results illustrate the impacts of the studied parameters and demonstrate a fourfold increase in d₃₁, compared to AlN, confirming the strong potential of Al_0.6Sc_0.4N for high-performance SMR transduction.