MEASURING LAYER THICKNESS OR COMPOSITION CHANGES

摘要

A method of measuring the thickness or the rate of change of thickness of a layer as the layer is being formed on a substrate, includes illuminating the layer through the substrate with low coherence light that transmits through the layer; collecting a portion of the reflected light from each optical interface of the substrate and layer with a low coherence interferometer; and, calculating the thickness or the rate of change of thickness of the layer according to the obtained interferometric data.