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

摘要

Charge trapping and detrapping characteristics have been studied on thin Si3N4SiO2 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.