Impact of silicon melt infiltration on the quality of cast crystalline silicon

摘要

Dislocation clusters are the most harmful defect in cast crystalline silicon, and it is very hard to determine the various dislocation origins. In this work, we design an experiment to investigate the impact of silicon melt infiltration on the crystal quality of cast crystalline silicon grown by different types of seeds. The results show that the infiltration of silicon melt at the ingot bottom will introduce more metal impurities, thus increasing the length of low minority carrier lifetime at the ingot bottom, which also proved by the numerical simulation of iron diffusion. Moreover, the solidified silicon melt would introduce local mechanical stress, which significantly increases the generation probability of defects in the mono-Si seeds and seed junctions, but not degrade the seeding quality of the poly-Si seeds. These results give a new insight to reduce dislocation origins for casting high-quality crystalline silicon ingots.