Distributed WIP control in advanced semiconductor manufacturing

A proven successful strategy to improve the responsiveness of manufacturing systems is to continuously enhance shop floor work-in-process (WIP) management. It is well known that a centralized WIP management system results in inflexibility and poor scalability for a manufacturing system on the shop floor. This article presents an easily manageable and well-distributed WIP management system to address these issues for an advanced semiconductor manufacturing system where WIP control plays a critical role. Multiple spawned WIP control modules from a central server are synchronized using the concept of Virtual Production Lines. By doing so the modularization of both software and hardware on the shop floor is realized. The manufacturing system governed by the proposed distributed WIP control system is flexible, re-configurable, and scaleable. Therefore, when changes occur on equipment or manufacturing cells, the adjustment will be limited within the relevant line, while the impact onto the rest of the system is very much limited. Because the change can be made easily, quickly, and cost-effectively, the advanced semiconductor manufacturing system using this distributed WIP control system thus becomes much more competitive.