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 degrees 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.