Correlation of annealing effects on local electronic structure and macroscopic electrical properties for HfO2 deposited by atomic layer deposition

Abstract

Atomic-scale electron spectroscopy is used to determine the local electronic structure of atomic-layer-deposited HfO2 gate dielectrics as a function of annealing conditions. Oxygen core-loss spectra from monoclinic crystallites exhibit a more strongly pronounced crystal-field splitting with increasing anneal temperature up to 1000 °C, consistent with a decrease in point defects. Concomitantly, electrical measurements of the same structures show a correlated reduction of fixed charge. An unintentional ∼5 Å SiO2 layer is observed at the top interface, between the HfO2 and poly-Si electrode. No Hf–silicate intermixing is detected at either interface on a scale down to 2 Å.