부산대학교 도서관

Variability in the manufacturing process (the coefficient of the OC curve), together with its counter measures, is the primary cause of long cycle times and reduced fab throughput. In an IC fab model, where substrate lots are processed through steps, and where each step is followed by a gap in processing, the wafer lots will spend more time in the accumulated transitions through the gaps than in-process. In these gaps non-linear growth of manufacturing variability occurs, through multiplication. Then, as this growth of variability is countered by stabilizing measures, such as wafer lot buffering and storage, cycle times are increased (and capacity reduced). An analysis of the above growth of variability is presented. Alternate product handling methods in the gap are studied to minimize this growth of variance. and so reduce fab cycle times (increase throughput).