A study of interfacial defects in HfO₂, LA₂O ₃, and GD₂O₃ thin films on silicon substrates

The characterisation, origin and passivation of electrically active interface and bulk defects present in high dielectric constant (high-k) thin films represents one of the major scientific and technological challenges associated with the integration of these films into silicon MOSFETs. In this work, we present experimental results which examine relatively high (>1×10¹¹cm^-2) electrically active interface defects which are commonly observed in (100)Si/SiO_x/highk/metal gate systems during high-k process development. This paper will extend previous studies on the (100)Si/SiO_x/HfO₂ system to include a comparative analysis of the density and energy distribution of interface defects for HfO₂, La₂O₃ and Gd₂O ₃ thin films on (100) orientation silicon formed by a range of deposition techniques. The analysis of the interface defect density across the energy gap, for samples which experience no H₂/N₂ or N₂ annealing following the gate stack formation, reveal a peak density ∼1×10¹²cm^-2eV^-1 to ∼1×10¹³cm^-2 eV^-1) at 0.83 to 0.92eV above the silicon valence band edge for the HfO₂, La ₂O₃ and Gd₂O₃ thin films on (100)Si, suggesting a common origin of silicon dangling bond (P_bo) centres for the dominant interface defects for the various (100)Si/SiO _x/high-k/metal gate systems.