Electrical characterization of atomic-layer-deposited hafnium silicate for alternative gate dielectric application

An electrical characterization of Al/Hf-Si-O/n-Si samples has been carried out. Hafnium-rich silicate films have been grown by means of atomic layer deposition (ALD). Capacitance-voltage (C-V), deep level transient spectroscopy (DLTS) and conductance transient (G-t) techniques have been used. Although as-deposited samples exhibit high interfacial state and disordered induced gap state densities, a post-metallization thermal annealing in vacuum under N₂ flow for 1 min. at temperatures between 600 and 730 °C clearly improves the interface quality. Moreover, both as-deposited and annealed samples show low flat-band voltage shift and hysteresis effect. These results confirm Hf silicate as a suitable candidate to replace SiO₂ as gate dielectric in future CMOS technologies.