Oxidation properties of silicon dots on silicon oxide investigated using energy filtering transmission electron microscopy

We used a side view transmission electron microscopy (TEM) technique which allows us to study the oxidation process of Si dots on SiO2 systematically for different dot sizes, oxidation times, and temperatures. Using energy fi ltering TEM (EFTEM) an excellent contrast between Si and SiO2 is achieved, independent from the crystal orientation. Si dots on SiO2 with initial diam eters from 10 to 60 nm were oxidized with different oxidation times at 850 degrees C. The resulting shapes of the SiO2 and the embedded Si cores were determined from the EFTEM micrographs. A. strong retardation of the oxidati on process compared to planar oxidation as well as a self-limiting effect f or long oxidation times are reported. Furthermore a pattern dependent oxida tion is observed, depending on the aspect ratios of the dots. (C) 1998 Amer ican Vacuum Society. [S0734-211X(98)04106-7].