Simulation Based Scheduling System in a Semiconductor Backend Facility

The semiconductor manufacturing process is usually divided in two parts: frontend and backend. In contrast to the frontend, where the manufacturing process is dominated by cluster-tools and cyclic routes, the backend has a predominant linear structure. In contrast to the frontend flow which is mostly controlled by dispatch rules, the backend process is suitable for real scheduling. A scheduling system for the backend of Infineon Technologies Dresden based on a discrete event simulation (DES) system was developed and tested in the real industrial environment. The simulation model is automatically generated from the databases of the manufacturer. The system is used for short term scheduling - from one shift up to one week. The paper will focus on the aspect of optimizing the process flow and calculating exact release dates for lots. The basic principles are applicable not only in the semiconductor industry but also in other industrial sectors