High interfacial quality metal-oxide-semiconductor capacitor on (111) oriented 3C-SiC with Al₂O₃ interlayer and its internal charge analysis

Metal-oxide-semiconductor (MOS) capacitors with various gate dielectrics were fabricated on (111) oriented n-type 3C-SiC. Deposited SiO₂ by sputtering without an interlayer (IL) and thermally grown SiO₂ show deteriorated capacitance-voltage (C-V) characteristics and high interface trap density (D _it) over 10¹¹-10¹² cm^-2 eV^-1. By inserting an IL, C-V and leakage current characteristics are improved. In particular, an atomic layer deposited (ALD) Al₂O₃-IL is suitable for 3C-SiC, which successfully achieved low D _it in the order of 10¹⁰ cm^-2 eV^-1. MOS capacitor with the same gate dielectric on n-Si shows contradictory characteristics. Structural analysis shows it is considered the flat and uniform interface at Al₂O₃/3C-SiC leads good electrical characteristics. The 3C-SiC MOS capacitor with Al₂O₃-IL showed slightly negative flatband voltage and it is induced by negative interfacial dipole generated at the Al₂O₃/3C-SiC interface. This 3C-SiC MOS structure can be fabricated at low process temperature (<600 C), which means the overall process for device application can be designed more flexibly.