Optimization of precursor pulse time in improving bulk trapping characteristics of atomic-layer-deposition HfO2 gate oxides

We report that precursor HfCl4 plays an important role in optimizing atomic-layer-deposition HfO2 bulk trapping characteristics. By systematic study, it has been observed that, under certain optimized precursor pulse time condition (450 ms pulse as compared to standard 150 ms), bulk trapping characteristics could be improved significantly without affecting the equivalent oxide thickness and leakage current characteristics of the devices. Slight improvement in mobility of the devices could also be obtained. Secondary-ion-mass-spectroscopy analysis shows that increase in the chlorine composition by increasing precursor pulse time could be attributed to the observed improvement. Drastic increase in pulse time (1500 ms) negates the benefit. (c) 2006 American Institute of Physics.