Measurement of Interface Trapped Charge Densities(Dit) in 6H-SiC MOS Capacitors

Abstract: At High oxidation temperature of SiC shows a tendency of carbide formation at the interface which results in poor MOSFET transfer characteristics. Thus we developed oxidation processes in order to get low interface charge densities. N-type 6H-SiC MOS capacitors were fabricated by different oxidation processes: dry, wet, and dry-reoxidation. Gate oxidation and Ar anneal temperature was 1150 ?. Ar annealing was performed after gate oxidation for 30 minutes. Dry-reoxidation condition was 950 ?, H2O ambient for 2 hours. Gate oxide thickness of dry, wet and dry-reoxidation samples were 38.0 nm, 38.7 nm, 38.5 nm, respectively. Mo was adopted for gate electrode. To investigate quality of these gate oxide films, high frequency C-V measurement, gate oxide leakage current, and interface trapped charge densities ( Dit ) were measured. The interface trapped charge densities ( Dit ) measured by conductance method was about 4 1010 [cm-1eV-1] for dry and wet oxidation, the lowest ever reported, and 1 1011 [cm-1eV-1] for dry-reoxidation

Keywords: SiC, MOS capacitor, oxidation, high-freqency C-V, Dit , conductance method, gate oxide leakage current densities.