Properties of HfO₂/Hf-silicate/Si structures with Hf-silicate formed by Hf metal deposition and subsequent reaction

Properties of the HfO₂/Hf-silicate/Si structure with the Hf-silicate layer which was formed by Hf metal deposition on Si and subsequent reaction of Hf with Si and oxygen during the HfO₂ deposition were studied. Post-deposition N₂ annealing reduced the equivalent oxide thickness (EOT) value and improved leakage characteristics of the HfO₂/Hf-silicate/Si structure. The EOT value was reduced from 2.70 nm to 2.23 nm after annealing. At a proper voltage of 2.5 V, which was defined as the difference between the applied gate bias and the flat band voltage, the leakage current density of annealed HfO₂/Hf-silicate/Si structure was 1.88 × 10^-7 A/cm² while that of as-formed HfO₂/Hf-silicate/Si structure was 1.92 × 10^-6 A/cm². The breakdown field increased from 7.29 MV/cm to 9.71 MV/cm after annealing.