Measurement and Analysis of Longitudinal and Transversal Effective Piezoelectric Coefficients (d33,f and e31,f) in 100 nm-500 nm Sc0.3Al0.7N films

High-quality piezoelectric ScAlN thin films with thickness under 500 nm are essential for achieving acoustic filters for 5G and 6G communications. In this work, 8-inch and 30% Sc doped AlN thin films with thickness of 100 nm, 300 nm, and 500 nm have been deposited by single target sputtering. The wafer-level piezoelectric coefficients, including d33,f and e31,f, have been characterized to evaluate the film quality and uniformity of the films. The mean values of the d33,f are 6.07 pm/V, 6.08 pm/V and 6.79 pm/V for 100 nm, 300 nm, and 500 nm films. The mean values of the e31,f are -1.16 C/m
²
, -0.99 C/m
²
, and -1.23 C/m
²
for 100 nm, 300 nm, and 500 nm films. The patterns of the wafer map are discussed with more film characterization results and the possible reasons leading to the observed distribution are further discussed.