X-ray spectroscopic examination of thin HfO2 films ALD- and MOCVD-grown on the Si(100) surface

HfO2 films 5 nm thick grown on Si(100) substrates by the methods of MOCVD hydride epitaxy and atomic layer deposition (ALD) are studied using X-ray photoelectron spectroscopy combined with Ar+ ion etching and X-ray reflectometry. It is found that (i) the ALD-grown HfO2 films are amorphous, while the MOCVD-grown films show signs of a crystal structure; (ii) the surface of the ALD-grown films is more prone to contamination and/or is more reactive; and (iii) the amount of interfacial silicon dioxide in the case of the MOCVD-grown film is greater than in the case of the films synthesized by ALD. It is also shown that the argon ion etching of the HfO2 film results in the formation of a metallic hafnium layer at the interface. This indicates that HfO2 can be used not only as a gate dielectric but also as a material suitable for fabricating nanodimensional conductors by direct decomposition.