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

In this research, the fabrication process of MISFET (Metal–Insulator–Semiconductor Field-Effect Transistor) structures with a SiO2/HfOxNy 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 HfOxNy 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 VFB, dielectric constant Ki, interface state trap density Dit, and effective charge Qeff. Subsequently, deposited HfOxNy 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 HfOxNy gate dielectric layer previously characterized. The transfer and output current–voltage (I-V) characteristics of the produced transistors are presented and discussed.