Manufacturing ownership of work-in-process control

IBM´s semiconductor manufacturing facility in Essex Junction, Vermont has made the transition from business-as-usual to continuous flow manufacturing. As a result, traditional tools used to control the production line have become ineffective, with new and more creative ways of managing work in process (WIP) required. This facility manufactures high-volume logic chips with multiple part numbers. Because of this volume, the technologies used to fabricate these devices must share tools and processes. The authors describe the system developed to control WIP in a logic facility with high-volume wafer starts and multiple part numbers. They also explain how manufacturing accepted ownership and responsibility for WIP control. Topics discussed include the control of wafer starts, overall WIP management, rules for product movement, the priority system, and communication methods. Since becoming an internal manufacturing responsibility, cycle times have decreased to targets 3×RPT (raw-process time), a significant factor in improving final test yields for wafers. WIP control has also helped increase weekly and monthly serviceability for volume and part-number mix, decrease the number of late lots in the line, and tighten the distribution of lots exiting the line