Hybridization of ellipsometry and XPS energy loss: Robust band gap and broadband optical constants determination of SiGe, HfON and MoOx thin films - Université Grenoble Alpes Accéder directement au contenu
Article Dans Une Revue Microelectronic Engineering Année : 2024

Hybridization of ellipsometry and XPS energy loss: Robust band gap and broadband optical constants determination of SiGe, HfON and MoOx thin films

Résumé

Efficiently passivating germanium (Ge) surfaces is crucial to reduce the unwanted recombination current in high-performance devices. Chemical surface cleaning is critical to remove surface contaminants and Ge oxides, ensuring effective surface passivation after dielectric deposition. However, Ge oxides can rapidly regrow upon air exposure. To understand the surface evolution after wet cleaning, we present a comprehensive study comparing HF and HCl deoxidation steps on p-type Ge surfaces and monitor the surface as a function of air exposure time. Distinct oxide regrowth dynamics are observed: HF-treated samples exhibit swift regrowth of all Ge oxide states, whereas HCl-treated Ge surfaces exhibit a lower concentration of low degrees of oxidation and slower or no regrowth of high oxide states even after 110 min of air exposure. In addition, the presence of Ge–Cl bonds induces different oxidation dynamics compared to the Ge–OH bonds resulting from HF cleaning. This leads to varying surface electronic band structures, with HF-treated Ge exhibiting a strong positive band bending (+0.20 eV). Conversely, HCl-treated samples display a lower band curvature (+0.07 eV), mostly due to the presence of Ge–Cl bonds on the Ge surface. During air exposure, the increased GeOx coverage significantly reduces the band bending after HF, while a constant band bending is observed after HCl. Finally, these factors induce a reduction in the surface recombination velocity after wet etching. Combining both chemical and field-induced passivation, HF-treated Ge without rinsing exceeds 800 μs.
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Dates et versions

hal-04509905 , version 1 (18-03-2024)

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Théo Levert, Alter Zakhtser, Julien Duval, Chloé Raguenez, Stéphane Verdier, et al.. Hybridization of ellipsometry and XPS energy loss: Robust band gap and broadband optical constants determination of SiGe, HfON and MoOx thin films. Microelectronic Engineering, 2024, 283 (1), pp.112117. ⟨10.1016/j.mee.2023.112117⟩. ⟨hal-04509905⟩
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