Silicon carbide formation by annealing C60 films on silicon

Abstract

Silicon carbide films were grown on (100) silicon substrates by deposition of 200-nm-thick C60 films, followed by annealing. The predeposited C60 is progressively destroyed by annealing, and carbon reacts with silicon to produce SiC. The reaction starts at the interface and continues by diffusion of silicon through the already formed SiC. At the lower temperatures (700 °C), the reaction is localized at the interface. Diffusion of silicon and formation of stoichiometric SiC requires annealing at 800 °C for t⩾100 min and at 900 °C for t⩾25 min. The stoichiometric films are uniform with a grain size of 20–40 nm. A diffusion coefficient of silicon in SiC of 4×10−15 cm2/s at 900 °C was determined. Because the diffusion of silicon is faster through preferential paths in the SiC film, such as grain boundaries and other crystalline defects, pits and voids are produced in the silicon substrate when the C60 predeposited film covers larger areas.