X-ray reflectometry analyses of chromium thin films

A series of thin (less than 100 nm) chromium films on Si and SiO2/Si substrates has been examined using X-ray reflectometry (XRR) and cross-section scanning electron microscopy. Comparisons of the measured film thicknesses from the two disparate methods were in good agreement. Because of this accord, it was possible to use these chromium thin films as model systems in order to probe the impact of both random and systematic errors on quantitative XRR measurements. In general, the errors associated with common XRR operations such as sample placement, system alignment, and choice of an instrumental broadening characteristic were much smaller than the statistical error obtained from a genetic algorithm fitting process to the experimental XRR curve.