Elimination of Voids at Interface of β-SiC Films and Si Substrate by Laser CVD

Void-free β-SiC films were deposited on Si(001) substrates by laser chemical vapor deposition using hexamethyldisilane(HMDS) as the precursor. The effect of the time of introducing HMDS, i e, the substrate temperature when HMDS introduced(T_(in)), on the preferred orientation, surface microstructure and void was investigated. The orientation of the deposited SiC films changed from 001 to random to 111 with increasing T_(in). The surface showed a layer-by-layer microstructure with voids above T_(in) ≥ 773 K, and then transformed into mosaic structure without voids at T_(in)= 298 K. The mechanism of the elimination of voids was discussed. At T_(in) =298 K, Si surface can be covered by an ultrathin SiC film, which inhibits the out-diffusion of Si atoms from substrate and prohibites the formation of the voids.