event logging

Event logging records all tool events for troubleshooting, analysis, and compliance, creating a comprehensive audit trail of equipment operation. Event types: (1) State transitions—idle→processing, offline→online; (2) Material events—wafer load, process start, wafer complete; (3) Operator actions—recipe select, parameter change, alarm acknowledge; (4) System events—software start, communication connect; (5) Alarm events—alarm set, alarm clear. Event attributes: event ID, timestamp, event description, associated data (lot ID, recipe, chamber), operator ID. Logging mechanisms: SECS/GEM event reporting (S6F11), equipment-native logging, MES transaction logging. Timestamp requirements: synchronized clocks across systems (NTP), millisecond resolution for detailed analysis. Event storage: log files (rolling, compressed), database records, historian systems. Event analysis applications: (1) Timeline reconstruction—what happened and when; (2) Cycle time analysis—time between events; (3) Failure analysis—events leading to failures; (4) Compliance—regulatory audit trails (FDA for medical devices); (5) OEE calculation—state time analysis from events. Log management: retention policies (months to years), backup procedures, access controls. Integration: events feed into fab dashboards, manufacturing execution systems, reporting tools. Critical for troubleshooting equipment issues, validating process execution, and demonstrating regulatory compliance.