Abstract
We show that high-angle annular-dark-field scanning transmission electron microscopy (HAADF-STEM) can be applicable to quantitative examination of Hf chemical distribution at a HfO2/SiO2 interface in a ultra-thin gate dielectric of an advanced MOS-FET. We examined how the annealing at 1000oC changes the chemical composition distribution at the interface and analyzed the observed change in the chemical composition in terms of Hf diffusion in SiO2. The estimated diffusion coefficient of Hf in SiO2 was 2.5×10-18 cm2/s and the diffusion length was 1.6×10-2 nm for annealing at 1000oC for 1 s. These indicate that high-temperature annealing used to fabricate Si devices, such as conventional dopant activation process, hardly changes the chemical composition distribution at the interface.
