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

Abstract

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 (~5nm) pedestal PECVD SiOx or SiOxNy, and top (~43nm) 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 electro-physical properties of MIS structures after the Post-Metallization Annealing, reduced Qeff/q and Dit 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.