The physicochemical and electrical properties of atomic-layer-deposited HfO2 films grown using O-3 generated with and without N-2 assistance were examined. Compared to the films grown using conventionally generated O-3 with N-2 assistance, the HfO2 film grown using O-3 generated without N-2 assistance had less metal impurities (mainly Cr) possibly due to the etching of stainless ozone delivery line. This induced a higher physical density of the film and a lower Si concentration in the film, which resulted in enhanced dielectric properties and reliability such as dielectric breakdown and resistance to constant voltage stress. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3430657] All rights reserved.