Characteristics of SiO₂/Si₃N₄/SiO₂ Stacked-Gate Dielectrics Obtained via Atomic-Layer Deposition

An interpoly-stacked dielectric film with a SiO₂/Si₃N₄/SiO₂/Si (ONO) structure was prepared via the atomic-layer deposition method. The multilayer structure of the ONO film with triple interfaces was investigated via medium-energy ion scattering (MEIS). A few defects in the interface layer of the ONO structure were detected. From the X-ray photoelectron spectroscopy (XPS) results, it was presumed that the interface layer with defects in the MEIS result is due to the formation of an oxynitride layer on the unstable and rougher Si₃N₄ layer via. By measuring the I–V characteristics, the leakage current density and breakdown field of the ONO film were determined to be 3.4 × 10⁻⁹ A/cm² and 10.86 MV/cm, respectively. By estimation the C–V curve, the flat band (V _FB) of the ONO film shifted to a negative voltage (−1.14 V), the dielectric constant (K _ONO) of the ONO film was 5.79, and the effective interface-trapped charge density of the ONO film was about 4.96 × 10¹¹/cm².