Hafnium silicate (HfSiO) has been identified as a promising candidate to replace silicon oxide/oxynitride as a high-kappa material for gate dielectric applications. Nitrided hafnium silicate has been found to have a number of advantages in film performance. However, two-step processes have been commonly used, i.e. the first step is the deposition of HfSiO film by CVD, ALD or other techniques, and the second step is film nitridation. In this research, HfSiON films (Hafnium silicon oxynitride, or nitrided HfSiO) were directly deposited on Si substrate by Chem. Vap. Depos. using trisilylamine (TSA) and tetrakis(diethylamido)hafnium(IV) (TDEAH) precursors. TSA, a highly volatile and carbon-free precursor, was used as the Si source and was delivered in pure vapor phase without heating. TDEAH was used as the Hf source and delivered by direct liquid injection (vaporizer). HfSiON films were deposited in a single step with no need of a post treatment process for nitrogen incorporation. The HfSiON films can be tuned in wide compositional (Hf, Si, O, N) ranges and high growth rates were achieved. The addition of NH(3) to the reactant gas stream was found to be able to deposit films with high and controllable N content. It was also found that NH3 had significant impact on film growth rate and composition. (c) 2007 Elsevier B.V. All rights reserved.