Der einfluss von strukturunregelmässigkeiten beim zusammenwachsen zweier aufdampfschichten auf das schichtdickenmessverfahren mit hilfe von vielstrahl-interferenzen

Abstract

By means of thickness measurements of vacuum-deposited thin Ag layers with island structure it was shown that the thickness measuring method of multiple beam interference results in much higher errors than it was supposed earlier. The uncertainties in measuring are caused by the fact that the reflecting layer used in performing the measurements does not grow in exactly the same way on the test layer as it does on the free substrate layer close by. The following data affect the amount of correction between the measured thickness and the mean geometrical thickness of the test layer: the mean roughnesses of the reflecting surfaces, cavities between the test layer and the reflecting layer, and gaps in the reflecting surfaces of the sample. The sources of error are best avoided by ultra-high-vacuum evaporation of the reflecting layer immediately after the evaporation of the test layer and by avoiding too high condensation temperatures. This procedure, however, highly limits the applicability of the multiple beam interference method.