Impact of Silicon Ion Irradiation on Aluminum Nitride-Transduced Microelectromechanical Resonators

Microelectromechanical systems (MEMS) resonators use is widespread, from electronic filters and oscillators to physical sensors such as accelerometers and gyroscopes. These devices' ubiquity, small size, and low power consumption make them ideal for use in systems such as CubeSats, micro aerial vehicles, autonomous underwater vehicles, and micro-robots operating in radiation environments. Radiation's interaction with materials manifests as atomic displacement and ionization, resulting in mechanical and electronic property changes, photocurrents, and charge buildup. This study examines silicon (Si) ion irradiation's interaction with piezoelectrically transduced MEMS resonators. Furthermore, the effect of adding a dielectric silicon oxide (SiO2) thin film is unveiled. Aluminum nitride on silicon (AlN-on-Si) and AlN-SiO2-Si bulk acoustic wave (BAW) resonators are designed and fabricated. The devices are irradiated using 2 MeV Si+ ions at various fluxes up to a total fluence of 5 x 10(14) cm(-2). A time anneal is conducted to characterize device recovery. Scattering (S-) parameters are measured in situ. Specific damage coefficients are derived to describe the radiation effect on resonant frequency (f(r)), quality factor (Q), motional resistance (R-m), and electromechanical coupling factor (k(eff)(2)). Furthermore, the damage coefficients for the bulk material properties of elastic modulus (E) and the piezoelectric coefficient (d(31)) are found.