Mechanism of V_FB / V_TH shift in Dysprosium incorporated HfO₂ gate dielectric n-Type Metal-Oxide-Semiconductor devices

The authors discuss temperature-dependent dysprosium (Dy) diffusion and the diffusion-driven Dy-silicate formation process in Dy incorporated HfO 2. The Dy-induced dipoles are closely related to the Dy-silicate formation at the high- k/ SiO2 interfaces since the VFB shift in Dy2 O3 is caused by the dipole and coincides with the Dy-silicate formation. Dipole formation is a thermally activated process, and more dipoles are formed at a higher temperature with a given Dy content. The Dy-silicate related bonding structure at the interface is associated with the strength of the Dy dipole moment and becomes dominant in controlling the VFB / VTH shift during the high temperature annealing in the Dy-Hf-O/ SiO2 gate oxide system. Dy-induced dipole reduces the degradation of the electron mobility. © 2011 American Vacuum Society.