Silicon carbide formation by annealing C-60 films on silicon

Silicon carbide films were grown on (100) silicon substrates by deposition of 200-nm-thick C-60 films, followed by annealing. The predeposited C-60 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 degrees C), the reaction is localized at the interface. Diffusion of silicon and formation of stoichiometric SiC requires annealing at 800 degrees C for t greater than or equal to 100 min and at 900 degrees C for t greater than or equal to 25 min. The stoichiometric films are uniform with a grain size of 20-40 nm. A diffusion coefficient of silicon in SiC of 4 x 10(-15) cm(2)/s at 900 degrees 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 C-60 predeposited film covers larger areas. (C) 1997 American Institute of Physics.