Thermal instability of silicon-on-insulator thin films measured by low-energy electron microscopy

Using low-energy electron microscopy (LEEM), we investigate the ultrahigh vacuum annealing of silicon-on-insulator (SOI) samples capped by a chemically-prepared oxide layer. Consistent with previous reports: (1) for T > 750 degrees C, the capping-oxide decomposes by void nucleation and growth, then (2) for T > 850 degrees C, the Si thin-film dewets from the SiO2 substrate. Here, we show that the morphological evolution of the surface during the dewetting process is dependent on the preparation of the SOI surface. Two dewetting pathways are evident in recent literature, we find that one evolution is characteristic of clean Si(100)-2 x 1 surfaces, while the other is correlated with surface contamination.