Annealing-temperature dependence: Mechanism of Hf silicidation in HfO₂ gate insulators on Si by core-level photoemission spectroscopy

We have investigated the mechanism of Hf silicidation from HfO₂ gate insulators on Si by high-resolution core-level photoemission spectroscopy with detailed annealing-temperature controlling. We have found that the silicidation temperature depends on the difference of the chemical states at the interfacial layer. The Hf-silicate layer which is more stable than the SiO₂ layer prevents the silicidation. In addition, silicidation processes also promote the formation of SiO₂. Chemical shifts in core-level photoemission spectra depend on the interfacial-layer thickness and SiO₂ concentration in the HfO₂ top layer, which are tunable by detailed annealing temperature.