Thermal stability of atomic-layer-deposited ultra-thin niobium oxide film on Si (100)

摘要

Ultra-thin Nb_2O_5 films with excellent uniformity have been grown on Si (10 0) by atomic-layer-deposition using Nb(OC_2H_5)_5 and H_2O precursors, and the corresponding thermal stability has been studied through atomic force microscope, transmission electron microscope and X-ray photoelectron spectroscopy. The results indicate that the ultra-thin (~3 nm) Nb_2O_5 film is gradually built up into distributed large islands with increasing rapid thermal annealing (RTA) temperature. Meanwhile, both crystalline and amorphous phases are formed in the matrix of Nb2_O_5 annealed at 700 °C. In terms of the as-prepared sample, an interfacial layer (IL) with a thickness of around 1.5 nm is observed, that is composed of niobium silicate (Nb-O-Si). Further, the high temperature RTA leads to a thickened IL, which is attributed to the formation of more Nb-O-Si bonds and new silicon oxide (Si-O-Si) adjacent to the Si (100).