The Defect Count Control Process Considering Wafer-to-Wafer and Lot-to-lot Variation

• Main Authors: Yuan-Kuang Lin, 林沅洸
• Other Authors: Lee-Ing Tong
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/06196865170654890251

碩士 === 國立交通大學 === 工業工程與管理系 === 91 === In integrated circuit (IC) fabrication, the appearance of wafer defects is unavoidable. Because defects influence the yield of a wafer, it is necessary to control defects to enhance the wafer quality. A Poisson distribution based c-chart is generally utilized to monitoring the wafer defects. However, the wafer size increases as IC fabrication techniques improve in the recently years, defects on wafer surface appear cluster phenomenon. The defect clustering will cause too many false alarms in the c-chart. In addition, the IC manufacturers usually obtain the defect counts from just one wafer sampled from a lot of twenty-five wafers to construct the c-chart. In such case, the wafer-to-wafer variation cannot be detected. The purpose of this study is to develop a procedure in which three control charts are included. An individual control chart and a moving range control chart are constructed to detect the wafer-to-wafer variation based on the modified defect counts using hierarchical clustering method to reduce the clustering impacts on the total number of defects. A c-chart is then employed to monitor the lot-to-lot variation if the wafer-to-wafer variation is stable. Cases to with simulated data are illustrated to verify the effectiveness of the proposed procedure.