Atomic layer deposition of Hf-Si-O and HfO2 using HfCl4, SiCl4, and H2O was studied. The growth per cycle and composition of Hf-Si-O films were analyzed as a function of the growth temperature, the pulse sequence, and the precursor doses. The growth of Hf-Si-O from HfCl4/SiCl4/H2O appeared to be determined not only by the -OH density but also by the -OH bonding mode. The HfCl4/SiCl4/H2O chemistry results in carbon-free films with low chlorine impurity content. The Hf-Si-O films of Hf-rich composition are meeting the leakage-current requirements for 45 nm technology node and below. (c) 2007 The Electrochemical Society.