Hafnium oxide thin films deposited by MOCVD were annealed in nitrogen at various temperatures. The as‐deposited films and annealed films were characterized using Auger electron spectroscopy (AES), atomic force microscopy (AFM), X‐ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The films were found to be slightly oxygen deficient. Angle‐resolved XPS revealed oxygen to be residing in two different chemical states, that of oxygen in hafnium oxide, and possibly, a hafnium silicate. Auger depth profiling revealed nitrogen enrichment in an interfacial layer at the film‐substrate interface, which could be the result of an ammonia pre‐treatment prior to deposition. The thickness of this interfacial layer was determined to be ∼ 15 A from TEM. Progressively larger grains were found from AFM measurements with increasing annealing temperature. © 2003 American Institute of Physics