Hafnium oxide (HfO2) thin films have received significant attention due to its excellent properties, such as large band gap, good thermodynamic stability, high density and high dielectric constant. The post-annealing temperature is also essential to their properties and application possibilities. In this work, HfO2 thin films were prepared on p-type silicon (100) substrates by remote plasma atomic layer deposition using tetrakis (ethylmethylamino) hafnium and remote oxygen plasma at 250 degrees C. The effect of rapid thermal annealing on the properties of the thin films was investigated using grazing incidence X-ray diffraction (GIXRD), X-ray photoelectron spectroscopy and field-emission transmission electron microscope (FE-TEM). FE-TEM and GIXRD results show that the as-deposited films are mostly amorphous and the crystallization initiates at about 500 degrees C. They also unveil a positive correlation between interface properties of the HfO2 thin films and a dependence of the crystallinity on annealing temperature.