Characterization of HfO2 on Hafnium-Indium-Zinc Oxide HIZO layer metal-insulator-semiconductor structures deposited by RF sputtering

The electrical properties of RF magnetron sputtered HfO₂ layers as dielectric and Hafnium-Indium-Zinc-Oxide HIZO as semiconductor in metal-insulator-semiconductor (MIS) structures are investigated. The dielectric constant of the HfO₂ layer was around 9 measured at 10 kHz. The critical electric field was higher than 5×10⁵ V/cm and the leakage current below 5×10^-9 A/cm². The effective charged density of interface states in the order of 5×10¹² cm^-2. Flat band shift due to polarization of the dielectric at voltage rage between -5 and 5 V is below 0.5 V. The RF deposited HIZO layer presents higher density of interface and bulk traps than similar layers deposited by other more complex techniques requiring higher processing temperature. However, results indicate that they can still be used in low voltage range amorphous oxide semiconductor thin film transistors AOSTFTs.