Fab cycle time improvement through inventory control : a wafer starts approach
Author(s)Ward, Matthew John
Leaders for Manufacturing Program.
Stephen C. Graves and Deborah J. Nightingale.
MetadataShow full item record
Intel's Colorado Springs wafer fabrication facility, known internally as F23, has undertaken several initiatives to reduce cycle time including High Precision Maintenance (HPM), content reduction through the application of Manufacturing Excellence (mX), effective utilization of production equipment, and aggressive inventory control. Each of these efforts has contributed to the marked improvement F23 achieved throughout 2006. F23's cycle time efficiency, the ratio of raw process cycle time to actual fab cycle time, improved from 12% (worst amongst Intel facilities) to greater than 35% (best amongst Intel sites), and overall cycle time was reduced by more than 61% in 2006. Inventory control was found to have a major impact on factory cycle time and performance. F23 controls its factory work-in-process, WIP, inventory through the F23 Wafer Starts Protocol. F23 utilizes Little's Law (Cycle Time = Inventory / Output) to identify target WIP inventory levels required to achieve particular cycle time goals. The target inventory is then achieved by modulating wafer starts. To do this, the Wafer Starts Protocol monitors the inventory of the overall fab and the constraint operations and suggests the amount of wafers to start for each shift.(cont.) Maintaining the target inventory level drives the overall factory cycle time towards the cycle time goal. Using the starts protocol, F23 has reduced its inventory by 44% while ramping factory output. During the implementation of this wafer starts protocol, F23 began tracking a new inventory metric to determine factory performance. Critical WIP ratio was introduced to evaluate the factory's inventory relative to the theoretical minimum inventory based upon a given factory output level and raw process time. F23 also found that this metric provides an effective comparison of inventory level between fabs. The Fab23 Wafer Starts Protocol is one of the ways in which F23 has applied Manufacturing Science tactics and principles to drive cycle time improvements. F23 has found that inventory control can have significant impacts on factory cycle time. This is one of the reasons why F23 was able to achieve dramatic cycle time improvement.
Thesis (M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management; and, (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division; in conjunction with the Leaders for Manufacturing Program at MIT, 2007.Includes bibliographical references (p. 59-60).
DepartmentSloan School of Management.; Massachusetts Institute of Technology. Engineering Systems Division.; Leaders for Manufacturing Program.; Massachusetts Institute of Technology. Engineering Systems Division; Sloan School of Management
Massachusetts Institute of Technology
Sloan School of Management., Engineering Systems Division., Leaders for Manufacturing Program.