Characteristics of ultra thin Hf-silicate gate dielectrics on Si _0.9954C_0.0046/Si heterolayers

For the first time, the characteristics of ultrathin (capacitance equivalent thickness = ∼1.4 nm) Hf-silicate gate dielectrics deposited by RF sputtering on tensile-strained Si_0.9954C_0.0046 layers are investigated. The formation of Hf-silicate film is confirmed by X-ray photoelectron spectroscopy. The physical thickness of ∼5.5 nm is measured by high-resolution transmission electron microscopy and the effective dielectric constant of κ ∼15.5 is calculated from the accumulation capacitance. The leakage current density of ∼1 × 10^-4 A/cm² at -2 V is significantly decreased as compared with SiO₂ for the same capacitance equivalent thickness.