Observation of Si-oxide interlayer and Si nano-crystallites embedded in an amorphous SiOx film

This study examined the rapid thermal annealing process of single crystal Si(0 0 1) substrates in oxygen ambient. A crystalline interlayer was observed between the amorphous silicon oxide (SiOx) film and Si(0 0 1) substrate. The Si nano-crystallites embedded in the amorphous SiOx film were studied by high-resolution transmission electron microscopy. The interface structure was affected by the annealing temperature. At 800 °C, no crystalline interlayer was observed, whereas a crystalline interlayer with the tridymite phase was observed when the sample was annealed at 1050 °C. A Si-oxide interlayer that contains oxygen interstitial atoms was formed when the Si(0 0 1) substrate was annealed at 1200 °C, wherein the thickness of the interlayer was limited to <2 nm. In addition, Si nano-crystallites were embedded in the amorphous SiOx film with a size ranging from 1.5 nm to 5 nm. The size of the Si nano-crystallites might be limited by diffusion during phase separation and by oxidation of the host Si atoms.