Electrical characterization of hafnium oxide and hafnium-rich silicate films grown by atomic layer deposition

An electrical characterization comparative analysis between Al/HfO2/n-Si and Al/Hf-Si-O/n-Si samples has been carried out. Hafnium-based dielectric films have been grown by means of atomic layer deposition (ALD). Interface quality have been determined by using capacitance-voltage (C-V), deep level transient spectroscopy (DLTS) and conductance transient (G-t) techniques. Our results show that silicate films exhibit less flat-band voltage shift and hysteresis effect, and so lower disordered induced gap states (DIGS) density than oxide films, but interfacial state density is greater in Hf-Si-O than in HfO2. Moreover, a post-deposition annealing in vacuum under N2 flow for 1 min, at temperatures between 600 and 730 °C diminishes interfacial state density of Hf-Si-O films to values measured in HfO2 films, without degrade the interface quality in terms of DIGS.