Technology and optimization of hafnium oxynitride (HfOxNy) thin-films formed by pulsed-DC reactive magnetron sputtering for MIS devices

Abstract

This study is devoted to the technology and optimization of pulsed-DC reactive magnetron sputtering of hafnium oxynitride (HfOxNy) thin-films. The fabrication process of HfOxNy films was optimized employing the Taguchi orthogonal tables approach leading to the material with possible best electrical parameters. During the optimization procedure, the parameters of dielectric films were monitored by means of electrical characterization of MIS structures with hafnium oxynitride as the gate-dielectric. The thermal stability of fabricated HfOxNy layers was also examined. The presented results have shown the improved electrical parameters of fabricated films after thermal treatment. Namely, we have observed beneficial flat-band voltage (Vfb) value, the disappearance of frequency dispersion of CV characteristics, reduced effective charge (Qeff/q), and interface traps (Dit) densities of examined MIS structures. However, the permittivity value is slightly lower as compared to reference samples. The superior stability of HfOxNy layers up to 800 °C was proved. Although the significant increase of crystalline phase in the layer bulk was observed, no deterioration of electrical properties or surface morphology has been noticed. The results presented in this study make the investigated HfOxNy fabricated using pulsed-DC reactive magnetron sputtering the possible candidate as a gate dielectric in MIS structures and devices.