Fabrication and characterisation of ScAlN -based piezoelectric MEMS cantilevers

Scandium (Sc) doping of aluminium nitride (AlN) increases the piezoelectric actuation potential due to substantially enhanced piezoelectric constants. This work demonstrates the fabrication of MEMS cantilevers actuated by sputter deposited Sc_xAl_1-xN thin films (x = 27 %) sandwiched between gold electrodes. Patterning of Sc_xAl_1-xN films is performed by a reactive ion etching process using SiCl₄. The dynamic actuation potential of the fabricated devices is evaluated with Laser Doppler Vibrometry and with electrical impedance spectroscopy measurements. When applying the Butterworth Van-Dyke equivalent circuit a significant increase of the effective transverse piezoelectric constant d₃₁ is demonstrated.