Wip control and calibration in a wafer fab

In this paper, a priority matrix table is used to assign priority to lots according to due date and workload information with the objective to keep lots going through the fab at the right pace to maintain WIP balance. Besides that, a WIP calibration method is proposed to recover WIP balance due to events such as unpredictable tool failure. The simulation results demonstrate that the proposed priority matrix table achieves a better WIP balance than FIFO (first in first out) and ODD (operation due date), and the WIP calibration method is able to correct for the WIP imbalance.