A framework for effective shop floor control in wafer fabs

In order to gain a competitive position within industry, in semiconductor fabs enormous efforts have been spent in developing different kinds of operational control strategies relating to work-in-process (WIP) and due date. This paper presents a framework to deal with shop floor control problems regarding WIP balance and due date control. The framework comprises four key components that are (1) Global and local rules; (2) Target WIP estimation; (3) WIP imbalance monitor and detection; (4) WIP imbalance calibration. These four components clearly focus on their own specific tasks and support each other, in such a way that we can manage to: (1) Improve efficiency and productivity such as achieving low WIP and cycle time while keeping good on-time delivery; (2) Enhance intelligence of automated manufacturing such as reducing WIP variability and smoothing material flow via automated WIP imbalance monitor and correction.