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

Abstract

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.