Structural and electrical characteristics of ALD-HfO2/n-Si gate stack with SiON interfacial layer for advanced CMOS technology

We report the fabrication of an ultra-thin silicon oxynitride (SiON) as an interfacial layer (IL) for n-Si/ALD-HfO₂ gate stack with reduced leakage current. The XRD, AFM, FTIR, FESEM and EDAX characterizations have been performed for structural and morphological studies. Electrical parameters such as dielectric constant (K), interface trap density (D_it), leakage current density (J), effective oxide charge (Q_eff), barrier height (Φ_bo), ideality factor (ƞ), breakdown-voltage (V_br) and series resistance (R_s) were extracted through C-V, G-V and I-V measurements. The determined values of K, D_it, J, Q_eff, Φ_bo, ƞ, V_br and R_s are 14.4, 0.5 × 10 ¹¹ eV⁻¹ cm⁻², 2.2 × 10⁻⁹ A/cm², 0.3 × 10¹³ cm⁻², 0.42, 2.1, −0.33 and 14.5 MΩ respectively. SiON growth prior to HfO₂ deposition has curtailed the problem of high leakage current density and interfacial traps due to sufficient amount of N₂ incorporated at the interface.