INTERFACIAL VOID FORMATION DURING VAPOR-PHASE GROWTH OF 3C-SIC ON SI(001) AND SI(111) SUBSTRATES - CHARACTERIZATION BY TRANSMISSION ELECTRON-MICROSCOPY

The formation and microstructure of voids at the interface between epi taxial films of 3C-SiC on Si(001) and Si(111) substrates have been inv estigated using cross-sectional transmission electron microscopy. SiC films were deposited using three different techniques; atmospheric pre ssure chemical vapor deposition (APCVD) in a hot-wall type reactor usi ng the silane-propane-hydrogen system in a substrate temperature (T-s) regime 900 degrees C to 1300 degrees C, reactive magnetron sputtering of Si target in mixed CH4/Ar discharge at T-s = 850 degrees C, and se quential sputtering from Si and C (graphite) targets in pure Ar discha rge at T-s between 710 degrees C and 850 degrees C. Voids formed in th e Si substrates with primary faceting on {111} planes and increased in size with increasing temperature. Truncation of voids was on {001} an d {113} planes as expected from shape equilibrium, but also truncation on apparent {011} facets were observed between inclined {111} planes as an effect of growth kinetics. The presence of voids resulted in an inhomogeneous residual strain state in the films during cooling from t he deposition temperature due to thermal mismatch to the substrate as evidenced by a significant broadening of the SiC(002) peak in X-ray di ffraction. Corresponding strain relaxation of the SiC film in the abse nce of voids resulted in plastic deformation of the Si substrate.