Temperature Coefficients of Transverse Elastic Properties of Scandium-Doped Aluminum Nitride (ScAlN) Thin Film Grown on Preformed Cavities

This report presents a fully coupled method to extract the temperature coefficients (TCs) of transverse elastic properties for 15% scandium (Sc)-doped aluminum nitride (AlN) thin film from resonant test structures. The ScAlN thin film here is only 0.3μm-thick, grown on pre-formed cavities embedded below 2μm-thick silicon (Si) membranes with a 0.2μm-thick molybdenum (Mo) electrode over ScAlN. The intended parameters are extracted by interacting between finite element model methods and electrical measurement data of fabricated resonators. The proposed method allows extraction of first and second order TCs for transverse elastic properties. By extracting elastic properties at each temperature point, we directly obtain individual elastic property dependence on temperature without having any prior assumptions on the polynomial order of this dependence. This study marks one of the first reports on TCs for transverse elastic properties of ScAlN thin film: in-plane Young’s modulus, in-plane shear modulus and in-plane Poisson’s ratio.