Importance of Qualification Management for Wafer Fabs

Due to the high investment costs of equipment for semiconductor manufacturing facilities (wafer fabs), it is crucial to ensure high utilization rates of the tools. By making the right qualifications, the overall machine and operations efficiency can be improved. Hence, efficient qualification management (QM) is a key factor for wafer fabs. In spite of this, not much has been investigated about what QM is, and what it can do for fab productivity. Only few articles treat the subject, and among these articles no author looks into the various aspects of QM and points out what the common challenges are. We will show that there is a need of a proper definition of QM for wafer fabs, and furthermore that it is an important area for further research. In this article we define what is meant with QM for wafer fabs and take a closer look into which areas of the wafer production are affected by QM. Furthermore we explain why proper QM in these areas is so important. We also review the lean literature area of QM for wafer fabs, and see how the content of earlier articles can be used to conclude what yet has to be conducted and what the new challenges are - where future research needs to be carried out. A conclusion on the work and future challenges is carried out; programs are needed that better display and visualize qualification settings; strategies to better handle process restrictions (such as costs, fault detection, capability, know-how, time); and performance measures that could be used in order to propose new qualifications should be further researched. Such measures could measure flexibility of process handling, cycle time reduction, fault detection frequency, yield rate or degree of reentrancy. Qualifications that optimize these measures will lead to a better performing fab.