Productivity improvement in a semiconductor wafer fab through transparent scheduling techniques

Summary form only given. This approach is designed for accuracy of results based on factory (discrete-event) simulations, malleability and transferability to any manufacturing scenario and market demand and transparency to the “human-factor” during the implementation phases. An information tracking framework is developed to integrate this effort with the shop-floor. Dynamic, real-time, discrete event simulations are used to determine the correct scheduling of factory resource. Constrained equipment are allocated a certain WIP capacity based on the simulation expectations and this WIP is regulated through a “drum-buffer-rope” approach linking one constraint to another for various process flows. These inputs are then continuously fed into a “virtual-factory” simulation-based scheduling system which feeds the Manufacturing Execution System (MES/CAM) with the correct sequence of lots to run on any equipment at any time. All this is accomplished in a finite, short-interval time and is a continuous improvement-based technique. The core factory simulation model used by the computer-generated schedules is thoroughly validated prior to any usage and is kept updated of the current factory scenario through a real-time interface to the MES system. This approach not only greatly reduces the cycle times of each process flow by regulating WIP and intelligent “push-pull” techniques, it also improves the On-Time Delivery (OTD) performance of the wafer fab. The “push-pull” is done completely transparent to the factory floor