Single-station performance evaluation and improvement in semiconductor manufacturing: A graphical approach

The relationships between key indicators of manufacturing system performance, such as cycle time (CT), throughput (TH), utilization, work-in-process (WIP), and the variability factor (to be defined shortly in the text), are complicated and difficult to quantify. In most cases, manufacturing managers cannot optimize one characteristic without adversely affecting another. For example, in order to reduce inventory and shrink time-to-market, one may need to lower the WIP level to reduce CT; however, too much WIP reduction can lead to unexpected station starvation (stoppage) and, thus, degrade TH. Low utilization of expensive equipment is also unacceptable, especially for advanced semiconductor manufacturing. This challenge caused difficulties for Chinese companies to keep up with the pace of China's development in becoming a global manufacturing center. To assist manufacturing managers in improving manufacturing system performance, we developed a graph decision aid for single-station semiconductor manufacturing systems.