Charge trapping/detrapping in Si3N4/SiO2 stacked dielectric layer deposited by LPCVD with in situ HF vapor cleaning

Charge trapping and detrapping characteristics have been studied on thin Si₃N₄/SiO₂ stacked dielectric layers processed in an integrated vacuum system with separate modules for HF vapor etching, silicon thermal oxidation and Si₃N₄ low pressure chemical deposition. At low field, polarization effects are observed, together with residual conduction. A large current flows at higher fields (>; 6MV.cm^-1), owing to Fowler-Nordheim conduction process; this current induces electron trapping. A zero-voltage stress during 15 minutes at 300°C completely sweeps out the trapped charge.