Charge trapping properties in TiO2/HfSiO/SiO2 gate stacks probed by scanning capacitance microscopy

The charge-trapping properties of the high-permittivity titanium oxide-hafnium silicate-silicon dioxide (TiO_2/HfSiO/SiO_2) gate stacks have been studied using scanning capacitance microscopy. From the bias stress examination of the gate stacks, we concluded that there were electron traps within the films, and these trap densities increased with an increase in the oxidation temperature used for the fabrication of TiO_2 top dielectrics. Furthermore, we found that the distribution of these charged defects was inhomogeneous within the gate stacks. These results are attributed to Ti diffusion through the dielectric layers, which caused electrical defects within the gate stacks.Y. Naitou, H. Arimura, N. Kitano, S. Horie, H. Ogiso, T. Hosoi, T. Shimura and H. Watanabe, "Charge trapping properties in TiO_2/HfSiO/SiO_2 gate stacks probed by scanning capacitance microscopy", Appl. Phys. Lett. 92, 012112 (2008) https://doi.org/10.1063/1.2828863