Physical properties of polycrystalline aluminium nitride films deposited by magnetron sputtering

Abstract

In combination with CVD diamond, an aluminium nitride (AlN) thin film is one of the most promising piezoelectric materials for surface acoustic wave (SAW) applications. One of the critical issues of SAW devices is the electromechanical coupling coefficient, which depends on the AlN film thickness and its mechanical and piezoelectric properties. In this work, properties of well (002) oriented AlN films deposited on silicon and fused quartz substrates by reactive DC pulsed magnetron sputtering were measured. The mechanical, electromechanical and optical properties of AlN film deposited under optimal conditions were determined. Novel methods, using an atomic force microscope (AFM), were used to measure the d 33 and d 31 piezoelectric coefficients. The d 33 piezoelectric coefficient measurement method allows a direct piezoelectric mapping. The experimental measurement results are in good agreement with the bulk values.