An Adaptive Fault Detection Strategy for Cz Crystal Growth Process

The monitoring and fault detection for the Czochralski (Cz) crystal growth process is important to ensure the quality of the produced monocrystalline silicon (MCS). The Cz process is a typical multimode industrial process, which makes the detection difficult in distinguish the change caused by the fault or mode switching. In this article, an adaptive fault detection strategy for Cz crystal growth process is proposed. First, quality-related variables are selected from numerous process variables, based on which the training dataset is constructed. Then, a fault detection model is built based on slowly varying feature (SVF) and statistic indicator. A model switching strategy and updating algorithm are designed to handle the abnormal situation caused by the mode switching or fault occurrence. Three representative experiments are conducted to verify the performance of the proposed strategy, including numerical cases, a publicly available dataset, and Cz crystal growth process from our laboratory.