Preparation of Hafnium Oxide Thin Films grown by Atomic Layer Deposition

Abstract

The growth of hafnium oxide thin films by atomic layer deposition was investigated in the temperature range of <TEX>$175-350^{\circ}C$</TEX> using <TEX>$Hf[N(CH_3)_2]_4\;and\;O_2$</TEX> as precursors. A self-limiting growth of <TEX>$0.6\AA/cycle$</TEX> was achieved at the substrate temperature of <TEX>$240-280^{\circ}C$</TEX>. The films were amorphous and very smooth (0.76-0.80 nm) as examined by X-ray diffractometer and atomic force microscopy, respectively. X-ray photoelectron spectroscopy analysis showed that the films grown at <TEX>$300^{\circ}C$</TEX> was almost stoichiometric. Electrical measurements performed on <TEX>$MoW/HfO_2$</TEX>(20 nm)/Si MOS structures exhibited high dielectric constant<TEX>$(\~17)$</TEX> and a remarkably low leakage current density of at an applied field of <TEX>$1.5-6.2\times10^{-7}A/cm^2$</TEX> MV/cm, probably due to the stoichiometry of the films.