Thin effective oxide thickness (∼0.5 nm) and low leakage current gate dielectric for Ge MOS devices by plasma nitrided Al2O3 intermediate layer

It is known that high dielectric constant (high-k) dielectric deposition on ultrathin GeO₂ would damage the quality of GeO₂ and degrade the interface. Both Al₂O₃ and AlN have been proposed as intermediate layer between high-k dielectric and GeO₂, but the process has not been optimized. In this work, it is observed that the N₂-plasma-nitrided Al₂O₃ is a good intermediate layer to suppress GeOx volatilization. Thin effective oxide thickness (~0.5 nm), low leakage current (<;4×10^-2 A/cm²), and acceptable interface state density (~4×10¹¹ 1/eV/cm²) have been demonstrated by the HfO₂/N₂-plasma-nitrided Al₂O₃/GeO_x/Ge MIS structure.