Deposition of HfO2 thin films by atomic layer deposition technique and investigation of current-transport mechanisms

The aim of this study, to deposit HfO2 (Hafnium dioxide) dielectric thin films by atomic layer deposition (ALD) technique at low growth temperature ranges and investigate the electrical properties of the grown films. For this purpose, HfO2 dielectric thin films were deposited on silicon (Si) substrates by ALD technique at a deposition temperature of 200 °C. To investigate the electrical properties of the deposited dielectric films and reveal current-conduction mechanisms, Al/HfO2/Si metal-oxide-semiconductor (MOS) capacitors were fabricated and current-voltage (I-V) and capacitance-voltage (C-V) measurements were performed. Using these measurement results, the dielectric constant of HfO2 films was calculated as 14 and the effective oxide charge density to be 2.3x1011 cm-2. It was found that the current-conduction mechanisms were strongly dependent on the applied electric field and Shottky emission and trap-assisted tunneling were found as the main conduction mechanisms at low and high electric fields, respectively.