Interfacial reaction of Si islands on SiO2 during high-temperature annealing

We examine the interfacial reaction between submicron Si islands and SiO2 during high-temperature annealing under ultrahigh vacuum, using atomic force microscopy and transmission electron microscopy. We show that Si island/SiO2 interfaces are much more reactive than interfaces of wetting thin Si films on SiO2. This indicates that important processes responsible for the reaction occur at the Si island edges. During the reaction removal of O atoms from the SiO2 side of the interface occurs, resulting in depression of the Si island/SiO2 interface. Our observations indicate that the interfacial reaction advances via O out-diffusion from SiO2 into the Si island, O lateral diffusion along the interface, SiO formation at the edge of the Si island, and SiO desorption from the surface. (C) 2010 American Institute of Physics. [doi:10.1063/1.3500506]