In this article, we report a specific feature for the distribution of silicon carbide nanocrystals formed by C implantation into SiO2 followed by thermal annealing. Cross-sectional transmission electron microscopy shows that silicon carbide nanocrystals (islands) are buried in the Si wafer at the SiO2/Si interface in a rectangular array (similar to 40X10 nm in dimension) and with a spacing of similar to 20 nm. High-resolution transmission electron microscopy examination shows that silicon carbide nanocrystals are epitaxial on the Si wafer and are absent in the SiO2 matrix. Photoluminescence peaked at 580 nm is observed for samples annealed at 1100 degrees C under 514 nm excitation, which is thought to arise from the embedded silicon carbide nanocrystals.