Study of interfacial reactions and phase stabilization of mixed Sc, Dy, Hf high- k oxides by attenuated total reflectance infrared spectroscopy

Grazing angle attenuated total reflectance Fourier transform infrared spectroscopy is applied to study ultrathin film Hf 4+, Sc 3+ and Dy 3+oxides, due to its high surface sensitivity. The (multi)metal oxides studied, are of interest as high- k dielectrics. Important properties affecting the permittivity, such as the amorphous or crystalline phase and interfacial reactions, are characterized. Dy 2O 3 is prone to silicate formation on SiO 2/Si substrates, which is expressed in DyScO 3 as well, but suppressed in HfDyO x . Sc 2O 3, HfScO x and HfO 2 were found to be stable in contact with SiO 2/Si. Deposition of HfO 2 in between Dy 2O 3 or DyScO 3 and SiO 2, prevents silicate formation, showing a buffer-like behavior for the HfO 2. Doping of HfO 2 with Dy or Sc prevents monoclinic phase crystallization. Instead, a cubic phase is obtained, which allows a higher permittivity of the films. The phase remains stable after anneal at high temperature.