A compositional library of Ag-Ti thin films was fabricated using combinatorial RF magnetron sputtering. The films exhibited a gradual compositional gradient across the substrate, ranging from Ag-rich to Ti-rich compositions. SEM analysis revealed a uniform thickness of approximately 150 nm for all films. The relationship between composition and properties was investigated, demonstrating that increasing Ag content led to decreased resistivity and increased density. These results can be attributed to the high electrical conductivity and density of Ag. To optimize SAW device performance, a balance between resistivity and density must be achieved. While Ag-rich films offer higher electrical conductivity, they may experience reduced inverse piezoelectric effects due to increased density. Conversely, Ag-poor films may have improved inverse piezoelectric effects but reduced electrical conductivity.

The elastic property of a copper (Cu) thin film was investigated using the surface acoustic wave (SAW) measurement technique. The Cu film was deposited on a quartz substrate using a direct current magnetron sputter and its surface morphology was inspected using atomic force microscopy. Time-domain waveforms of the SAW on the film were acquired at different propagation distances to estimate the Young’s modulus of Cu such that the experimentally-obtained dispersion curve can be compared to the analytical result calculated using the Transfer Matrix method for curve-fitting. Results showed that the film’s elastic property value decreased by 18.5% compared to that of the bulk state, and the scale effect was not significant in the thickness range of 150-300 nm, showing good agreement with those by the nanoindentation technique. The property, however, increased by 15.5% with the grain coarsening.