HfO2 films were grown by atomic layer deposition (ALD) from Hf[N(CH3)(C2H5)](4) and H2O on Si(100) substrates. The thickness of 5-45 nm thick films on HF-etched Si was proportional to the number of growth cycles. Crystallization was observed in the 30-45 nm thick films, containing the monoclinic HfO2 polymorph. Films with thicknesses lower than 10 nm were amorphous. The effective permittivity of the dielectric films varied between 6.5 and 17. The leakage and capacitive characteristics did not show any clear dependence on the HfO2 growth temperature. (C) 2004 The Electrochemical Society.