Pre-Epitaxy Backside Iron Contamination Leads to Cluster Cone Defect in Shallow Trench Isolation

Epitaxy is a key process at the front end of semiconductor manufacturing, the defect on the epitaxial film greatly affects the yield and reliability of the final product. Previous studies have focused on the impurities on the front side of the substrate silicon leading to epitaxial defects. However, in our study, the backside of the substrate silicon was contaminated with metal impurities before epitaxy, which led to an interesting clustered cone defect in the isolation trench. We carried out a series of experiments and proposed a possible hypothesis about the formation mechanism of the cluster cone defect. Furthermore, a possible solution for such a defect was also provided and verified to avoid the potential loss of yield and reliability.