Investigation of bilayer HfN_x gate insulator utilizing ECR plasma sputtering

Abstract

In this paper, we have investigated bilayer HfN_x gate insulator utilizing ECR plasma sputtering especially for the electrical properties with metallic-phase HfN_0.5 gate electrode which was formed by in-situ process. After PMA of 500°C/10 min in N₂/4.9%H₂ ambient, the bilayer of HfN_1.3 (1.7 nm)/HfN_1.1 (0.9 nm) gate insulator formed on Si(100) showed the EOT of 0.61 nm, leakage current density (@V_FB −1 V) of 5.5 × 10⁻³ A/cm² and density of interface states (D_it) of 5.5 × 10¹¹ cm⁻² eV⁻¹. The n-MISFET with bilayer HfN_x gate insulator exhibited saturation mobility (μ_sat) of 47 cm²/(V s), which higher than the device with directly deposited HfN_1.3 gate insulator. HfN_x interfacial layer (IL) with low nitrogen concentration was found to significantly improve the interface properties of HfN_x gate stacks.