Abstract: Automated defect sourcing systems identify root-causes of yield excursions due to contamination, process faults, equipment failure and/or handling. They perform this function in timely manner and provide accurate and timely feedback to address and contain the sources of yield excursion. A signature repository stores known wafer surface manufacturing defect types as set of rules. The signature of a manufacturing defect pattern is associated with the equipment or process that causes the defects, and is used to source the manufacturing defects and to provide process control for changing and/or stopping yield excursion during fabrication. A defect signature rule-based engine matches wafer defects against the signature repository during wafer fabrication. Once the defect signature is detected during fabrication, handling and/or disposing the root-cause of the corresponding defect is facilitated using messages according to an event handling database.