%0 Conference Paper
%A Clement Lorenzo, Marta
%A Olivares Roza, Jimena
%A Iborra Grau, Enrique
%A González Castilla, Sheila
%A Sangrador García, Jesús
%A Rimmer, Nick
%A Rastogi, A.
%A Ivira, B.
%A Reinhardt, Alexandre
%B 22nd European Frequency and Time Forum (EFTF) 2008
%C Toulouse, Francia
%D 2008
%F upm:3928
%I Braunschweig
%T Aluminium Nitride Solidly Mounted BAW Resonators with Iridium Electrodes
%U http://oa.upm.es/3928/
%X In this work we investigated the performance of aluminium nitride (AlN)-based solidly mounted resonators (SMR) made with iridium (Ir) bottom electrodes. Ir/AlN/metal stacks were grown on top of insulating Bragg mirrors composed of alternate λ/4 layers of silicon oxi-carbide (SiOC) and silicon nitride (Si3N4).Ir electrodes of various thicknesses were electron-beam evaporated on different adhesion layers, which also acted as seed layers. AlN was deposited by sputtering after conditioning the Ir electrode by a soft-etch with Ar+ ions, which was essential to achieve high quality AlN films. The structure and morphology of the different layers were analysed by x-ray diffraction (XRD) and atomic force microscopy (AFM). The frequency response of the SMRs was assessed by measuring the input scattering parameterS11 with a network analyzer. The experimental results were fitted to the Butterworth-Van Dyke circuital model. The effective electromechanical coupling factor k2eff, and the quality factor Q of the resonators were derived from the experimental data. The influence of the thickness, crystal quality and roughness of the Ir bottom electrodes on the performance of the resonators was investigated.