Fabrication and Electrical Characterization of MISFET Structures with SiO₂/HfO_xN_y Gate Dielectric Stack

In this research, the fabrication process of MISFET (Metal-Insulator-Semiconductor Field-Effect Transistor) structures with a SiO₂/HfO_xN_y stack as a gate dielectric was developed, providing a viable device platform for future ion-sensitive and biosensing transducer integration. Hafnium Oxide-Nitride films were deposited using reactive magnetron sputtering in an O₂/N₂/Ar gas mixture. The thickness of HfO_xN_y films was measured using spectroscopic ellipsometry. To evaluate the electrical properties, MIS (metal-insulator-semiconductor) structures were formed by Al metallization. Then layers were electrically characterized using I-V and C-V measurements. This allowed the extraction of key electrical parameters such as flat-band voltage V_FB, dielectric constant K_i, interface state trap density D_it, and effective charge Q_eff. Subsequently, deposited HfO_xN_y layers were annealed in a post-deposition annealing (PDA) process (40 min, 400 °C, 100% N₂) followed by a second electrical characterization. Finally, MISFET structures were developed, incorporating the HfO_xN_y gate dielectric layer previously characterized. The transfer and output current-voltage (I-V) characteristics of the produced transistors are presented and discussed.