Passivation effect of SiN/sub x/:H films formed by microwave remote plasma CVD for P-diffused substrates

Abstract

Hydrogenated silicon nitride (SiN/sub x/: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 SiN/sub x/: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 SiN/sub x/:H layers deposited by SiH/sub 4//NH/sub 3/ ratio of 15/40 exceeded those of chemically passivated (CP) substrates with iodine/ethanol solution. The best thickness of SiN/sub x/: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 SiN/sub x/:H single layer was reduced compared with SiO/sub 2/ films and SiN/sub x/:H/SiO/sub 2/ double layers deposited on non-diffused wafers. The effect of forming gas anneal (FGA) on the effective lifetimes at different temperature (600-800 /spl deg/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.