Structural and electrical characteristics of thin erbium oxide gate dielectrics

A high-$k$ erbium oxide thin film was grown on silicon substrate by reactive rf sputtering. It is found that the capacitance value of $Er2O3$ gate dielectric with TaN metal gate annealed at $700°C$ is higher compared to other annealing temperature and exhibits a lower hysteresis voltage as well as interface trap density in $C-V$ curves. They also show negligible charge trapping under high constant voltage stress. This phenomenon is attributed to a rather well-crystallized $Er2O3$ and the decrease of the interfacial layer and Er silicate thickness observed by x-ray diffraction and x-ray photoelectron spectroscopy, respectively.