Abstract
In order to evaluate the thickness of SiO2 films on Si substrates accurately for the development of a thickness standard material, we suggested the application of a heat cleaning method in atmosphere to remove surface contamination. We observed the changes in the X-ray reflectivity profiles before and after heating in order to estimate the influence of the surface contamination on the thickness evaluation. The reflectivity increased, especially in the higher angle region, by the heat cleaning of the samples in atmosphere. The change in the reflectivity was attributed to the decrease in the surface roughness caused by the contaminant desorption. The thicknesses estimated by the fitting analysis of the sample after heating also decreased by the order of 0.1-0.2 nm. The surfaces of the heated sample were recontaminated in atmosphere; this recontamination was observed as the increase in the evaluated thickness at a rate of approximately 0.01 nm/h.
