High permittivity quaternary metal (HfTaTiOx) oxide layer as an alternative high-κ gate dielectric

Abstract

The authors investigated the optical and electrical properties of the high permittivity $\left(\kappa \right)$ metal oxides, HfTiO and HfTaTiO, using $\mathrm{Hf}{\mathrm{O}}_2$ as a reference and compared their material properties against their electrical performance. HfTiO has a higher $\kappa$ value but its band offset is relatively smaller and, therefore, it has greater gate leakage current than $\mathrm{Hf}{\mathrm{O}}_2$ . HfTaTiO has an even higher $\kappa$ value which compensates for the impact of its small band offset. In addition, $\mathrm{Hf}{\mathrm{O}}_2$ was found to have more defect states than the other two films, which caused a larger hysteresis in the capacitance-voltage scan and degraded channel mobility.