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

Abstract Ultra-thin Nb 2 O 5 films with excellent uniformity have been grown on Si (1 0 0) by atomic-layer-deposition using Nb(OC 2 H 5 ) 5 and H 2 O 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 2 O 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 Nb 2 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 (1 0 0).