Phase transformations in hafnium dioxide thin films grown by atomic layer deposition at high temperatures

High-temperature cubic phase of HfO2 was observed by reflection high-energy electron diffraction in nanocrystalline thin films grown by atomic layer d eposition from HfCl4 and H2O at substrate temperatures of 880-940 degreesC. The phase was formed at properly chosen precursor doses and it was observe d on the surface of films, which according to X-ray diffraction data consis ted of monoclinic HfO2. The thickness of the surface layer, in which the cu bic phase appeared, was estimated to be 5-10 nm. According to Auger electro n spectroscopy data, formation of the cubic phase was accompanied with an i ncrease in the ionicity of O-Hf bonds. (C) 2001 Elsevier Science B.V. All r ights reserved.