Modeling the growth of PECVD silicon nitride films for crystalline silicon solar cells using factorial design and response surface methodology

Silicon nitride was grown on polished Si wafers by a parallel plate PECVD reactor. Reaction gases were NH₃ and 3% SiH₄ in Ar and the RF frequency was 13.56 MHz. The film thickness and refractive index were measured by an ellipsometer. The results were analyzed using the response surface methodology. The results indicate that the silane-to-ammonia flow rate ratio is the dominating parameter when determining the refractive index and that the total gas flow rate and the chamber pressure dominate the growth rate, whereas RF power has a less strong impact on growth rate and no impact on refractive index. The previous results will be used when growing passivating ARCs on three grain Si solar cells