The influence of varied sputtering condition on piezoelectric coefficients of AlN thin films

Under the consideration of clamping effect and constraint between the film and the substrate, the method of piezoelectric coefficients measurement is different between thin film and bulk material. The piezoelectric coefficients (d₃₃) of AlN thin films were measured using the method of periodic compression force in this study. The d₃₃ measurements of AlN thin films were performed on AlN/SiO₂-Si and AlN/LiNbO₃ multilayer structures, respectively. The preferred c-axis orientated AlN thin films were deposited by reactive rf magnetron sputtering. The main difference of the two substrates is the piezoelectricity of the LiNbO₃ and non-piezoelectricity of the SiO₂-Si. The correlation between growths parameters and piezoelectric coefficients will be investigated in this study. It showed that the values of d₃₃ are increased as the increase of X-ray diffraction intensity. From the view of full-width at half maximum (FWHM), it also showed that the values of d₃₃ increased as the decrease of the FWHM. The piezoelectric characteristic of thin films showed an obviously variation of AIN thin film. The microstructure controlled by the sputtering parameters has a great influence on thin film piezoelectricity.