Effects of ultra-shallow ion implantation from RF plasma onto electrical properties of 4H-SiC MIS structures with SiOx/HfOx and SiOxNy/HfOx double-gate dielectric stacks

摘要

This study presents the first results concerning technology and characterization of MIS structures with double gate dielectric stacks fabricated on 4H-SiC substrates after ultra-shallow fluorine and nitrogen implantation from RF plasma. The gate stack was composed of ultra-thin (similar to 5 nm) pedestal PECVD SiOx or SiOxNy, and top (similar to 43 nm) HfOx fabricated by means of reactive magnetron sputtering process. The RF implantation procedure was optimized in order to obtain the maximum concentration of implanted ions very close to the SiC/dielectric interface. The electrical characterization of fabricated MIS structures have shown the improvement of electrophysical properties of MIS structures after the Post-Metallization Annealing, reduced Q(eff)/q and D-it values after RF ion implantation of MIS devices compared to corresponding reference structures, as well as the increase of effective permittivity for the double-gate dielectric stack with pedestal SiOxNy layer. Furthermore, all examined SiC-MIS test structures fabricated after plasma implantation processes are characterized by a reduction in a leakage current density, and very significant increase of the mean breakdown voltage value. (C) 2017 Elsevier B.V. All rights reserved.