Excimer Laser Cleaning Research Articles

Time-resolved ellipsometry

An ellipsometer is described which is capable of measuring one of the related ellipsometric parameters N, S, or C as a function of time. The ellipsometer is of the standard polarizer–compensator–sample–analyzer type, in which the analyzer is a Wollaston prism. An analysis is presented of the errors resulting from misalignment of the azimuths of the various elements from an incorrect phase shift of the compensator and from sample surface effects. The time resolution of the ellipsometer is limited only by the rise time of the photodetector and by the digitization rate of the data acquisition system. Picosecond time resolution is possible, in principle, using a streak camera as both detector and digitizer. Submicrosecond operation of the time-resolved ellipsometer is demonstrated in a study of pulsed excimer laser cleaning of a silicon surface in air.