Ion knock-on broadening effects in Auger sputter profiling studies of ultrathin SiO2 layers on Si

Publisher Website
Google Scholar
Abstract
Ultrathin layers of SiO2 on Si (less than ∼100 to 200 Å) show a reduction in the measured width of the Si–SiO2 interface when profiled using ion sputtering. Although previously attributed to the intrinsic properties of thin oxides or surface roughening due to ion‐beam etching, this effect is predominantly caused by ion knock‐on broadening or knock‐on enhanced diffusion. It is important to realize that this effect is an artifact of the sputtering process, and not a property of the system under study. A model is developed based on the spatial distribution of the energy deposited by the sputtering ions to explain the observed reduction in measured interface width. This model is compared with interface widths obtained using Auger electron spectroscopy from identically grown thermal SiO2 samples which have been thinned by chemical etching to eliminate oxidation kinetic effects.