Raman spectroscopy (RS), x-ray dimaction (XRD), and reflection high-energy electron diffraction (RHEED) were
applied for a structural analysis of ZrO2 and HfO2 thin films grown on Si substrates by chloride atomic layer deposition
(ALD). The RS measurements were performed on freestanding ZrO2 and HfO2 films. In these conditions, high-quality
micro-Raman spectra of 100-660-nm-thick films were obtained in the whole range of interest, 80-800cm-1. The
structural data determined by RS were complemented by the XRD and RHEED data. As a result, it has been ascertained
that at the initial stage of the ALD growth of ZrO2 and HfO2 films at 500 and 600 °C, respectively, metastable phases
form and dominate. In the case of ZrO2 films, this phase has been identified as the tetragonal polymorph. Over the film
thickness range of 56-660 nm, the absolute amount of the tetragonal ZrO2 has been shown to be almost constant, with its
relative amount decreasing and the amount of the monoclinic phase increasing when the film thickness increases. Neither
RS nor XRD allowed any unambiguous identification of the metastable phase in the otherwise monoclinic HfO2 films.
According to the RHEED data, at the very initial stage of the HfO2 growth, cubic HfO2 is present.