Influence of growth parameters and systematical analysis on 8-inch piezoelectric AlN thin films by magnetron sputtering

To achieve high quality of AlN piezoelectric thin films with highly c-axis orientation and low stress, 1-mu m thick AlN films were deposited by magnetron sputtering on the 8-inch Mo/AlN-interlayer/Si substrate under different growth conditions. Through optimization, the full width at half maximum (FWHM) of AlN (002) rocking curve is as low as 0.905 degrees. The relationship among the quality, morphology, stress, and further the growth mechanism of AlN films were systematically analyzed. The AlN films exhibit different morphology and residual stress, which can be attributed to the effect of different deposited conditions on the sputtering particles and the grains of films. Besides, the pseudo-Voigt function was theoretically used to evaluate the grain size and stress of AlN film. The calculation results suggest that it is feasible to use pseudo-Voigt function to evaluate the grain size and the stress of AlN film, while the evaluation requires a uniform grain distribution.