High-speed ellipsometer and its application to the process line

A new high speed photometric ellipsometer consisting of simple optical elements, electronics, and personal computer is developed. This ellipsometer, extremely fast and having no moving parts, is suitable for measuring film thickness moving fast in the process line, where no conventional ellipsometer can be applied. This new ellipsometer is applied to measure oil film thickness of order 0 approximately 100 angstrom coated on tinned steel sheet moving at a speed of 5 m/s. In this case, two lasers with different wavelength are used as light sources to elliminate influence of roughness of substrate's surfaces. Oil film thickness measured by the new ellipsometer and those by conventional off-line method (hydrophil balance method) agree within the uncertainty of 1 mg/m2 (corresponding thickness is about 11 angstrom).