Root Cause Analysis in Float-Zone Crystal Growth Production using Fishbone diagram and Association Rule Mining

Float-Zone (FZ) crystal growth process is a critical process for producing ultra-pure silicon crystal with extremely low impurities, particularly low oxygen level. However, the occasional oxide problem on polysilicon surface acts as a impediment to the process efficiency. Hence, this study aims to address this problem by conducting root cause analysis. Specifically, association rule mining is applied on a dataset with the input identified by a fishbone diagram from different aspects. The results showed that a high moisture level from the early phase could potentially be a critical contributor to the oxide problem, thereby indicating the next step of research – exploring the underlying reasons for the high moisture level.