The distribution of chemical elements in Al- or La-capped high-κ metal gate stacks

Abstract

The spatial distribution of chemical elements is studied in high-κ, metal-gated stacks applied in field effect transistors. Using the transmission electron microscope (TEM)-based analytical techniques electron energy-loss spectroscopy (EELS) and energy-dispersive x-ray spectroscopy, it is demonstrated that Al2O3 and La2O3 capping layers show distinctly different diffusion profiles. The importance of the EELS collection angle is discussed. Popular chemical distribution models that assume La-rich interface layers are rejected.