Atomic and electronic structure investigations of HfO ₂/SiO ₂/Si gate stacks using aberration-corrected STEM

Aberration correction in scanning transmission electron microscopy represents a major breakthrough in transmission electron microscopy, enabling the formation of sub-Angstrom probe sizes. Thus, electron microscopy achieved single atom sensitivity. Here, we show how this technique with its unique spatial resolution in combination with high-resolution electron energy-loss spectroscopy can be used to investigate atomic and electronic structures of semiconductor interfaces with single atom sensitivity. We employ a Si/HfO ₂/SiO ₂/Si high-k dielectric interface to show the presence of single Hf atoms in the SiO ₂ interlayer. Furthermore, we demonstrate how local dielectric properties and local band structure information can be obtained by electron energy-loss spectroscopy.