The electrical properties of the HfO2 gate dielectrics prepared under different annealing conditions were investigated. We found that the large leakage currents are mostly associated with the high trap density in the dielectric films. Several charge transport mechanisms have significant contributions to the large leakage current. To study the reliability of the gate dielectric film grown under different annealing conditions, the capacitors were stressed at constant voltages for different durations. The overall current-voltage and capacitance-voltage characteristics suggest that the annealing conditions have to be optimized in order to have a proper dielectric film. Time dependent dielectric breakdown (TDDB) study shows that for oxide film of same physical thickness, the time to breakdown falls with the increase in capacitor area. (c) 2005 Elsevier Ltd. All rights reserved.