ALD deposited ZrO2 ultrathin layers on Si and Ge substrates: A multiple technique characterization

• Published in: Microelectronic engineering 2013-12, Vol.112, p.208-212
• Main Authors: Botzakaki, M.A., Xanthopoulos, N., Makarona, E., Tsamis, C., Kennou, S., Ladas, S., Georga, S.N., Krontiras, C.A.
• Format: Article
• Language: English
• Subjects: ALD; Atomic force microscopy; Atomic structure; Deposition; Electrical characterization; Germanium; High-k; Metal oxide semiconductors; MOS; Silicon substrates; Valence band; XPS; Zirconium dioxide; ZrO2
• ISSN: 0167-9317; 1873-5568
• DOI: 10.1016/j.mee.2013.03.002

•Ultra thin ZrO2 layers were grown by ALD technique on p-Si, strained Si and p-Ge substrates.•The stoichiometry, thickness and valence band electronic structure were obtained through XPS analysis.•AFM measurements suggest that the deposition method is successful for the formation of ultrathin ZrO2.•C–V and G–V characteristics reveal typical MOS structure behavior, with Dit values of the order of 1012eV−1cm−2. In this study, a multiple characterization technique of ultrathin ZrO2 films, deposited on high mobility substrates such as strained-Si (s-Si) and p-type Ge (p-Ge) by Atomic Layer Deposition (ALD), is presented. For reasons of comparison ZrO2 films on p-type Si (p-Si) where also studied. The stoichiometry, chemical composition and valence band electronic structure are characterized by X-ray Photoelectron Spectroscopy (XPS). For p-Si and s-Si substrates the ZrO2 valence band edge is found at 2.4±0.2eV while for the p-Ge substrate, the valence band edge is found at 2.6±0.2eV. Furthermore, Atomic Force Microscopy (AFM) measurements reveal that, all tested samples are in general smooth (0.2–0.3nm roughness) and uniform. MOS capacitive structures were fabricated, using Al as a gate metal, and characterized electrically through C–V and G–V measurements. The typical behavior of a MOS structure has been revealed. Dit values, of the order of 1012eV−1cm−2, were calculated using Hill–Coleman method.