Chemical reaction and metallic cluster formation by annealing-temperature control in ZrO2 gate dielectrics on Si

Thermal stability of the ZrO2∕Zr–silicate∕Si structure and the Zr–silicide formation were investigated by photoemission spectroscopy depending on the annealing temperature in ultrahigh vacuum. By the annealing below 860°C, the interfacial layer thickness of the Zr–silicate decreased although the ZrO2 top layer was not affected. The annealing at 860°C caused the interfacial Zr–silicate layer to disappear. By the annealing above 860°C, the metallic Zr components appeared and the metallic clusters were formed. High-resolution photoemission spectra have revealed that the clusters consist of a ZrSi2 layer. Valence-band spectra depending on the annealing temperature provide us with the information about the crystallization in the ZrO2 layer.