Local composition analysis of SiC microstructures formed by ion projection in silicon using energy filtered TEM in combination with FIB specimen preparation

Buried silicon carbide (SiC) microstructures with lateral dimensions in the μm range were formed by high-dose projection of 1.5 MeV C2+ ions in Si(100) at different doses and temperatures and subsequent annealing for 10 h at 1250 °C. Sections of individual SiC microstructures were prepared for cross-sectional transmission electron microscopy (TEM) analysis using a focused ion beam (FIB). Besides the possibility to select an individual microstructure, the FIB technique has the advantage of producing specimen foils of uniform thickness. Therefore, it was possible to map the carbon concentration of microstructures by energy filtered TEM (EFTEM) using the CK absorption edge without the need of any sample thickness correction. Local overstoichiometric (>50%) carbon concentrations are shown to be correlated to the formation of an amorphous phase in the SiC and to significant swelling visible at the Si wafer surface 2 μm above.