Method for Determining the Density and Elastic Constants of a Thin Film
Original Publication Date: 1988-Feb-01
Included in the Prior Art Database: 2005-Feb-14
An improved technique is described to independently measure the density and two elastic constants of an isotropic thin film deposited on an anisotropic substrate. The method uses an acoustic phase measuring system together with a directional acoustic lens to measure the perturbation of a Rayleigh (surface acoustic) wave. The surface waves are produced by a defocused directional acoustic lens (see Hildebrand and Lam, Appl. Phys. Lett . 42, 413 (1983)). The velocity perturbation is measured by comparing the phase of the central ray with the phase of the leaky surface acoustic wave (SAW) as the lens is scanned over an anisotropic substrate/isotropic thin film step (see K. Liang et al., Appl. Phys. Lett . 41 1124 (1982); K. Liang et al., Rev. Sci. Instr ., 57, 446 (1986); and K. Liang et al., IEEE Trans.