Properties of HfO2/Hf-Silicate/Si Structures with Hf-Silicate Formed by Hf Metal Deposition and Subsequent Reaction

Abstract

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.