The Impact of Different Diffusion Temperature Profiles on Iron Concentrations and Carrier Lifetimes in Multicrystalline Silicon Wafers

In this study, we investigate the influence of different diffusion temperature profiles on the interstitial iron concentration before and after contact firing. It is shown that the positive influence of a low-temperature anneal after phosphorus diffusion is strongly reduced after contact firing as the formed precipitates dissolve again. On the other hand, a dissolution peak before the diffusion aims on a decrease in precipitate density and, therefore, leads to a reduced interstitial iron concentration especially after firing. The physical mechanisms during diffusion and firing are investigated with Sentaurus Process simulations. Furthermore, lifetime improvements in standard multicrystalline material could be achieved applying the dissolution peak before diffusion.