Void nucleation in thin HfO2 layer on Si

We examined void nucleation in a thin HfO2 film on Si at 820–920 °C in an ultrahigh vacuum. The clustering of mobile species on the HfO2 surface led to the opening of micron-scale voids containing Hf silicide. The incubation period observed for void nucleation exhibited transition of decomposition process with activation energies of 2.3 eV (<890 °C) and 11 eV (>890 °C). We propose that the former energy corresponds to the creation of mobile species and the latter to the decomposition of the HfO2 film under the cluster.