Characteristics of high-quality HfSiON gate dielectric prepared by physical vapour deposition

This paper presents a method using simple physical vapour deposition to form high-quality hafnium silicon oxynitride (HfSiON) on ultrathin SiO₂ buffer layer. The gate dielectric with 10 Å (1Å = 0.1 nm) equivalent oxide thickness is obtained. The experimental results indicate that the prepared HfSiON gate dielectric exhibits good physical and electrical characteristics, including very good thermal stability up to 1000°C, excellent interface properties, high dielectric constant (κ = 14) and low gate-leakage current (I_g = 1.9 × 10⁻³ A/cm²@V_g = V_fb − 1V for EOT of 10 Å). TaN metal gate electrode is integrated with the HfSiON gate dielectric. The effective work function of TaN on HfSiON is 4.3 eV, meeting the requirements of NMOS for the metal gate. And, the impacts of sputtering ambient and annealing temperature on the electrical properties of HfSiON gate dielectric are investigated.