HfO2 thin films were deposited on HF-dipped Si wafers at 300 °C using an atomic-layer-deposition technique with N-containing Hf[N(CH3)2]4 and H2O as the precursor and oxidant, respectively. A thin interfacial SiNx layer was spontaneously formed at the HfO2/Si interface during film growth. This interfacial SiNx layer prevented substrate Si diffusion into the HfO2 film. Therefore, the reduction in the capacitance density as a result of post-annealing at 800 °C was minimized. The leakage current density was also reduced due to the more amorphous-like structure of the film. Furthermore, the interfacial trap density (Dit) of <5×1010 cm−2 eV−1 near the midgap energy states was obtained from an as-deposited film that has a capacitance equivalent thickness of 1.8 nm. This Dit value was comparable to that of the well-grown SiO2/Si interface. However, the Dit slightly increased after post-annealing as a result of the increased N concentration at the interface, but it was still <1×1011 cm−2 eV−1. © 2003 American Institute of Physics.