Effect of Silicon Surface Cleaning on Electrical Properties of As-Deposited Atomically Layer-Deposited (ALD) HfO2 Films Obtained From Tetrakis(dimethylamino)Hafnium (TDMAH) and Water

The paper presents the results of an experimental study of the electrical properties of ultrathin as-deposited HfO2 films prepared at 200 degrees C by atomic layer deposition (ALD) from the reaction between tetrakis(dimethylamino) hafnium (TDMAH) and water as function of silicon surface terminations. The comparison of high frequency C-V plots recorded on Al-HfO2-Si MOS capacitors prepared on Si-OH and Si-H terminated silicon and thermally annealed in nitrogen at 250 degrees C have indicated a two-fold smaller oxide trapped charge, and a 5% higher effective dielectric constant (9.95) for capacitors prepared Si-OH with respect the same capacitors processed on Si-H terminated silicon. Weibull plots of the HfO2 breakdown events at constant current injection through the dielectric as a function of charge to breakdown have revealed an increased reliability of the HfO2 films deposited on Si-OH terminated silicon substrate, in terms of a much smaller number of early breakdown events and higher capability of carrying electrical charges, before failure. The results are explained in terms of reaction mechanism between TDMAH and silicon termination and its role on interface and bulk HfO2 film properties.