Application of LFB acoustic microscope to film thickness measurements

Abstract

The line-focus-beam (LFB) acoustic microscope is applied to measure the precise thickness of thin films using the velocity dispersion of leaky waves in layered samples. The measurement principle and accuracy are investigated theoretically and experimentally, taking a configuration of Au-film on fused quartz. It is demonstrated at 225 MHz that the thickness resolution better than 2 Å is achieved for a 3000 Å sample using leaky pseudosurface acoustic waves.