Growth kinetic and composition of the interfacial layer for RF sputtering Al₂O₃ layer on germanium

Abstract

Purpose

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.

Design/methodology/approach

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.

Findings

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.

Originality/value

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.

Citation

Sahari, S.K., Kashif, M., Mohamed Sutan, N., Embong, Z., Nik Zaini Fathi, N.A.F., Hamzah, A.A., Sapawi, R., Yeop Majlis, B. and Ahmad, I. (2017), "Growth kinetic and composition of the interfacial layer for RF sputtering Al₂O₃ layer on germanium", Microelectronics International, Vol. 34 No. 2, pp. 64-68. https://doi.org/10.1108/MI-12-2015-0099