Blocking of deuterium diffusion in poly-Si/Al2O3/HfxSi1−xO2/SiO2 high-k stacks as evidenced by atom probe tomography

Abstract

Hydrogen (H) plays an important role in determining the reliability and performance of HfO2- and Al2O3-based high-k dielectric electronic devices. In order to understand H behavior, deuterium (D), an isotope of H, was introduced into the poly-Si cap of Al2O3/HfxSi1−xO2/SiO2 high-k stacks by ion implantation. Atom probe tomography was used to image the D distribution in samples annealed under different conditions. The results clearly demonstrated that the D atoms were trapped at the interface of poly-Si and Al2O3 after annealing at 900 K for 10 min. Thus, it is possible that Al2O3 blocks the H atoms at the surface, preventing them from diffusing into the high-k dielectrics during the H2 annealing process in current fabrication technology. The current work also exhibits an example of investigating H behavior in semiconductors by atom probe tomography.