Simultaneous Measurement of Film Surface Topography and Thickness Variation using Three-wavelength Interferometry

Model-based Separation Algorithm of Two Overlapped Sinusoidal Signals

Abstract

Conventional transparent film thickness measurement methods such as spectroscopy are basically capable of measuring a single point at a time, and the spatial resolution is limited. We have developed a novel areal film thickness and topograpgy measurement method by three-wavelength interferometry. It estimates both the profiles of front and back surfaces and the thickness distribution of a transparent film simultaneously by model-based separation of two overlapped signals in the interferogram. The validity of the proposed method is proved by computer simulations and preliminary experiments.