Quality, Reliability, and Yield Monitoring Tools For An IC Fabrication Line

AT&T traditionally monitored its wafer fabrication facilities with high volume Dynamic Random Access Memory (DRAM) production. The DRAM was an excellent indicator of the facility's status. DRAMs are highly diagnosable and are suitable tools for both yield improvement and reliability testing. Application Specific Integrated Circuits (ASIC) fabricated on the same line benefited from the DRAM data. Termination of AT&T's DRAM business forced a change in the production monitoring program because low volume ASIC circuits do not by themselves provide the data that the DRAM provided, and they are difficult to analyze for yield improvement and reliability failures. This paper describes the tools and procedures that have been developed for monitoring the Quality, Reliability and Yield in AT&T's wafer fabrication facilities. The tools include a Line Monitor, Zone Monitors, test equipment, data handling facilities and a yield model.