Patent ID: 6019000
Filing Date: 2000-02-01
Classification: G01H,G01N

Abstract:
An apparatus for measuring properties including thickness of one or more films on a chamber member, comprising:one or more source transducers, each configured to excite acoustic waves at a plurality of frequencies in the substrate at a corresponding excitation location;one or more receiving transducers, each configured to detect acoustic waves at a probe location in the substrate, wherein the acoustic waves include reflected waves received at the probe location due to a composite reflection of the excited acoustic waves from the one or more films, wherein the one or more source and the one or more receiving transducers are not necessarily different transducers and the probe and excitation locations are not necessarily different locations; anda processing module coupled to the receiving transducers configured to determine the properties of the one or more films from measurements including a phase measurement at each of a plurality of frequencies on a selected waveform group.