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This paper investigates and discusses the effect of wet chemical cleaning; Hydrochloric Acid (HCl) and Hydrofluoric Acid (HF) to the growth of interfacial layer between high-k material (Al 2 O 3 ) and Ge (100) surface. Characterization and morphology techniques using Field Emission Scanning Electron Microscope (FESEM) was carried out to determine the thickness of interfacial layer between Al 2 O 3 and Ge (100) surface. Results of this study showed that an HF treatment gives a rougher surface of Al 2 O 3 than HCl treatment.Both wet chemical cleaning resulted with step and terrace trend of Al 2 O 3 and interfacial layer. This may be due to initial Ge surface just after HF cleaning is rougher than the initial Ge surface after HCl cleaning.

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 Al 2 O 3 on the Ge substrate. The purpose of this paper is to report on growth kinetics and composition of IL between Al 2 O 3 and Ge for HCl-and HF-last Ge surface. Design/methodology/approach-After wet chemical cleaning with HCl or HF, Al 2 O 3 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 Al 2 O 3 /Ge that will lead to the improvement in Ge metal insulator field effect transistors (MISFETs) application.

Abstract. The different cleaning solution; HCl and HF solution are used to remove the suboxide and oxide component on Ge surface. The HCl cleaning results chlorine (Cl) termination on Ge surface whereas no Fluorine (F) termination was observed just after HF cleaning. The growth of Ge oxide is studied after treated with HCl cleaning on two surface orientations; (100) and (111), respectively in dry oxygen ambient and cleanroom air by spectroscopic ellipsometry (SE) and x-ray photoelectron spectroscopy (XPS). A clear step and terrace trend was observed for the oxidation growth of Ge (100) and Ge (111) in dry oxygen ambient compared to in clean room air. This trend shows the difference in surface reaction of Ge oxidation as humidity varies. The stability of chlorine termination of Ge (111) than Ge (100) explains the slower growth of oxidation in dry oxygen ambient.

The understanding of chemical bonding structure of high k dielectrics/Germanium (Ge) interface is upmost importance in order to form a good quality dielectric/Ge interface in fabricating Ge metal oxide semiconductor field effect transistor (MOSFETs). In addition, there is still no detail explanation on the interfacial growth of dielectrics/Ge under the influenced of different temperature of post deposition anneal. In current work, the effects of post deposition anneal (PDA) temperature between 400°C and 600°C on the chemical composition of interfacial layer between Ge and Al 2 O 3 were examined by X-ray photoelectron spectroscopy (XPS). Investigation on thermal stability and structural characteristics for gate structure of Al 2 O 3 dielectric grown on Ge by RF sputtering was done by analyzing X-ray photoelectron spectroscopy (XPS) spectra. It is observed that the oxygen deficient region in interfacial layer (IL) is enhanced rather than fully oxidized Al 2 O 3 with increased PDA temperatures. These undesired phenomena caused shrinkage of IL at Ge/Al 2 O 3 interface at higher temperature of 600°C.