We investigated the effectiveness of SiN and SiON barrier layer in controlling the interfacial reaction between Atomic Layer Deposited (ALD) HfO2 film and the Si substrate. The HfO2 film was found to form silicate and silicide at the interface with Si after 5 min post deposition annealing in Ar at 800 and 1000 degrees C as observed by scanning transmission electron microscopy/electron energy loss spectroscopy and X-ray photoelectron spectroscopy analysis of the annealed ALD films. A 1.5 nm-thick Chemical Vapor Deposited (CVD) SiN was found to effectively prevent interfacial reaction during annealing at temperatures up to 1000 degrees C. Also, SiON deposited either by annealing the Si substrate in N2O (low N-content) or by annealing CVD SiN in O-2 (high N-content) was found to prevent silicate and silicide formation at the interface. (C) 2008 Elsevier B.V. All rights reserved.