Thickness Measurement of Aluminum Thin Film using Dispersion Characteristic of Surface Acoustic Wave

In this study, we suggest a method to measure the thickness of thin films nondestructively using the dispersion characteristics of a surface acoustic wave propagating along the thin film surface. To measure the thickness of thin films, we deposited thin films with different thicknesses with range of 200~1000 nm on a Si(100) wafer by controlling the deposition time by DC sputtering technique. The thickness of the thin films was measured using a scanning electron microscope. Subsequently, the surface wave velocity of the thin films with different thickness was measured using V(z) curve method of scanning acoustic microscopy. The correlation between the measured thickness and surface acoustic wave velocity was verified. The wave velocity of the film decreased as the film thickness increased. Consequently, film thickness can be determined by measuring the dispersion characteristics of the surface acoustic wave velocity.