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The quality of GeOx–Ge interface and the equivalent oxide thickness (EOT) are the main issues in fabricating high-k/Ge gate stack due to the low-k of GeOx interfacial layer (IL). Therefore, a precise study of the formation of GeOx IL and its contribution to EOT is of utmost importance. In this study, the GeOx ILs were formed through post-oxidation annealing of sputtered Al₂O₃ on the Ge substrate. The purpose of this paper is to report on growth kinetics and composition of IL between Al₂O₃ and Ge for HCl- and HF-last Ge surface.

After wet chemical cleaning with HCl or HF, Al₂O₃ was grown onto the Ge surface by RF sputtering. Thickness and composition of IL formed after post-anneal deposition at 400°C in dry oxygen ambience were evaluated as a function of deposition time by FESEM and characterized by X-ray photoelectron spectroscopy, respectively.

It was observed that the composition and thickness of IL were dependent on the starting surface and an aluminum germinate-like composition was formed during RF sputtering for both HF- and HCl-last starting surface.

The novelty of this work is to investigate the starting surface of Ge to IL growth between Al₂O₃/Ge that will lead to the improvement in Ge metal insulator field effect transistors (MISFETs) application.