GROWTH OF SIC FILMS VIA C-60 PRECURSORS AND A MODEL FOR THE PROFILE DEVELOPMENT OF THE SILICON UNDERLAYER

We report on an experimental and theoretical study of the growth of Si C films and of the profile development of the silicon underlayer. SIC features were grown via the direct reaction of the silicon substrate w ith C-60 precursors. Two masking configurations were used to investiga te the effects of bulk and surface diffusion on SiC film growth. Witho ut a diffusion barrier (i.e., a patterned SiO2 mask with regions of si licon initially exposed directly to C60) voids formed in the substrate beneath the growing SiC layer, which ultimately controlled the final thickness of the SiC film. Pronounced faceting was observed at the ear ly stages of growth on crystalline silicon. When a tungsten diffusion barrier was used to prevent bulk diffusion (i.e., tungsten covering si licon in non-SiO2 masked regions), significant undercutting resulted b eneath the oxide and SiC layers without void formation. A profile simu lation was developed to model the time evolution of the silicon underl ayer when this diffusion barrier is used. The simulation incorporated an adatom hopping and surface diffusion model to describe the generati on and transport of silicon atoms along the evolving profile. A single fitting parameter was required. The agreement between simulation and experiment was good, and a corresponding value of the hopping coeffici ent was calculated. As an alternative to direct reaction with the sili con substrate, we also demonstrate experimentally that silicon atoms c an be co-sublimed with fullerenes to produce SiC films on wafer surfac es, which avoids the consumption of substrate material. Co-sublimation was used to create SiC membranes and also to coat silicon microcantil evers. Force-deflection measurements for the microcantilevers revealed that the stiffness properties were enhanced with the application of a SIC film and that the co-sublimed SiC had mechanical properties like those of bulk material. (C) 1998 American Vacuum Society. [S0734-2101( 98)08404-8].