Electrical characterization of MIS structures with HfOx gate dielectric films fabricated on silicon substrates modified by ultra-shallow ion implantation from RF plasma

The feasibility of ultra-shallow fluorine and nitrogen implantation from RF plasma into silicon substrates, and the correlation between implantation process parameters, and electro-physical properties of obtained Metal-Insulator-Semiconductor (MIS) structures with hafnium oxide (HfOx) layer as a gate dielectric was investigated. The analysis of electrical characteristics of MIS structures proved that almost all fabricated structures after plasma implantation are characterized by lower flat-band voltage (Ufb) value (in absolute values) and lower effective charge (Qeff) in comparison to reference samples. However, the limitation of such an improvement is the specified value of power applied to the reactive chamber (i.e., 120 W). MIS structures are also characterized by a lower leakage current and very significant increase in the breakdown voltage (Ubr) value. The structural characterization has demonstrated that both types of plasma implantation result in the introduction of the relatively high concentration of fluorine and nitrogen into silicon subsurface area. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)