Transparent Film Thickness Measurement by Three-wavelength Interference Method

An Extended Application of Global Model Fitting Algorithm

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 propose a novel areal film thickness measurement method by extending the Global Model Fitting algorithm developed for three-wavelength interferometric surface profiling. It estimates the film thickness distribution from a color image captured by a color camera and three-wavelength light source. The validity of the proposed method is proved by computer simulations and preliminary experiments. It is possible to determine 2D absolute film thickness with a simple optics.