Characterization of an enhanced thermal oxide layer on 6H–SiC using ion irradiation

The oxidation rate of the Si-face of 6H–SiC(0001) was significantly enhanced by applying an ion irradiation technique. Such significant enhancement of the oxidation rate is ascribed to the breakage of the strong covalent bond of the SiC lattice using low-energy ion irradiation and the resultant chemical reactions. Thermal oxide layers on the ion irradiated SiC surface were studied by ellipsometer, secondary ion mass spectrometry (SIMS), cross-sectional transmission electron microscope (XTEM), I-V meter and C-V meter. The refractive indices for the samples, which were irradiated with high doses and oxidized for a long time, are 1.46±0.005, which well matches that of SiO2 thermally grown on non-irradiated SiC substrates. SIMS analysis of the enhanced thermal oxide layer shows that thermal oxidation forms the homogeneous SiO2 layer. The cross sectional TEM image of the enhanced thermal oxide layer shows an abrupt interface and good crystallinity of the substrate near the interface. The electrical properties of the interface between the thermal oxide layer and the SiC substrate depend on the residual damage induced by ion irradiation. A longer oxidation time and/or post oxidation annealing improve the electrical properties.