Atomically-Engineered Interfaces Between Crystalline-Ge Substrates and i) Nanocrystalline HfO2 and ii) Non-Crystalline Hf Si Oxynitride High-K Dielectrics

This paper presents a spectroscopic study of interfacial bonding and substrate gate dielectric reactions for crystalline Ge-high-K gate dielectric hetero-structures. A novel processing sequence has been developed for i) depositing HfO2 and Hf Si oxynitrides (HfSiON) onto N-passivated Ge(111) and (100) substrates in an attempt to prevent subcutaneous oxidation of the Ge substrate during dielectric deposition, and then ii) eliminating these Ge-N interfacial bonds during 650-800°C rapid thermal annealing in Ar. This approach has been motivated by previous spectroscopic studies which have demonstrated that the band-gaps of GeO2 and Ge3N4 are reduced with respect to their Si counterparts, and cannot be used as interfacial layers (ILs) on n-type Ge substrates, or in n-metal oxide semiconductor field effect transistors (n-MOSFETs) in which a p-type Ge substrate has been inverted. Changes in interface bonding as a function of post-deposition annealing for Ge/HfO2 and HfSiON, and HfO2/HfSiON stacks have been studied by X-ray absorption and photoelectron spectroscopies, revealing i) intrinsic, or pre-existing conduction and valence band edge defects, and ii) process-induced changes in band edge defects as well. [DOI: 10.1380/ejssnt.2009.381]