Passivation effect of SiNx:H films formed by microwave remote plasma CVD for P-diffused substrates

Hydrogenated silicon nitride (SiNx:H) films on the P-diffused and non diffused substrates were deposited by remote plasma-enhanced chemical Vapor deposition (RPECVD) to study the passivation effect on recombination lifetimes and obtain the optimized conditions for SiNx:H deposition. The effective carrier lifetimes were strongly affected by gas ratio, temperature and deposition time conditions. The maximum effective carrier lifetimes in substrates passivated with SiNx:H layers deposited by SiH4/NH3 ratio of 15/40 exceeded those of chemically passivated (CP) substrates with iodine/ethanol solution. The best thickness of SiNx:H deposited on non-diffused wafer and the optimized thickness of P-diffused one are different, and the latter is more thicker. The reflection of SiNx:H single layer was reduced compared with SiO2 films and SiNx:H/SiO2 double layers deposited on non-diffused wafers. The effect of forming gas anneal (FGA) on the effective lifetimes at different temperature (600-800 degrees C) were examined. The effective lifetime increased in a short time and degraded with increasing annealing time. Fast degradation mechanism at higher annealing temperatures was observed.