Formation of Ultra-Thin Silicon Oxynitride Films by Low-Energy Nitrogen Implantation.

Abstract

AbstractOxynitrides (SiOxNy) have been used as gate insulators for submicron devices [1]. The present work reports the oxynitride formation at SiO2/Si structure by N2+ implantation at low energies. Si substrates were implanted with N2+ ion beams (energy = 5.6 keV and dose =1×10 ions/cm2), annealed at 950°C for 30 min in N2 ambient, oxidized at 950°C in O2 + 1% TCE environment and annealed at 950°C for 30 min in N2. After these process steps, the oxynitride formation was investigated by FTIR, SIMS and ellipsometric analysis. These physical characterizations revealed the presence of Si-0 and Si-N bonds. The film thicknesses and refractive indexes were 7 nm and 1.62, respectively. The dielectric constant = 4.39 and effective charge density = 7xl010 cm–2 were determined by C-V, indicating that the SiOxNy films formed are suitable gate insulators for MOS devices.