Ternary rare-earth metal oxide high-k layers on silicon oxide

Abstract

Ternary oxides, $\mathrm{Gd}\mathrm{Sc}{\mathrm{O}}_3$ , $\mathrm{Dy}\mathrm{Sc}{\mathrm{O}}_3$ , and $\mathrm{La}\mathrm{Sc}{\mathrm{O}}_3$ , deposited by pulsed laser deposition using ceramics targets of stoichiometric composition, were studied as alternative high-$k$ gate dielectrics on (100) Si. Their physical characterization was done using Rutherford backscattering, spectroscopic ellipsometry, x-ray diffraction, and transmission electron microscopy on blanket layers deposited on (100) Si, and electrical characterization on capacitors. It is found that $\mathrm{Dy}\mathrm{Sc}{\mathrm{O}}_3$ and $\mathrm{Gd}\mathrm{Sc}{\mathrm{O}}_3$ preserve their amorphous phases up to $1000°\mathrm{C}$ . Other encouraging properties for high $k$ applications were demonstrated, including $k$ -value $\sim 22$ , almost no hysteresis or frequency dispersion in $C–V$ curves, and leakage current reduction comparable to that of $\mathrm{Hf}{\mathrm{O}}_2$ of the same equivalent oxide thickness.