In this paper, ultra-thin Nd2O3 dielectric films are deposited on p-type silicon substrates by advanced atomic layer deposition method. Nd (thd)3 and O3 are used as the reaction precursors separately. The as-grown samples are annealed in N2 atmosphere in a temperature range of 700900 ℃. The samples are investigated at room temperature by X-ray photoelectron spectroscopy and the changes of the film composition at different annealing temperatures are discussed in detail. For a higher precursor temperature of 185 ℃ in the deposition process, the ratio of oxygen to neodymium atoms for the as-grown film is 1.82, which is close to the stoichiometry. Dielectric constant increases from 6.85 to 10.32.