Contamination Control: a systems approach

Contamination influences a wide variety of industrial processes. For complex systems, contamination control, the collective effort to control contamination to such a level that it guarantees or even improves process or product functionality, offers a way for finding workable solutions. Central in the approach is the system, i.e. a product, a process, or a production tool. Contamination control has its focus on the system as a whole. A solution must be compliant with every aspect of the system. Therefore, the basis of every contamination control investigation is system analysis. In this phase, all sensitive objects and process steps are described and the system requirements must be listed, following which the relevant contamination types can be identified and levels can be determined. When these steps are taken, a ranking of all contamination issues can be made by FMEA, after which a solution for the failure mode with the highest score can be developed. Three main directions for solutions can be distinguished: prevention, cleaning, and monitoring. The choice between the three options depends on the maturity of the process and how much actually the observed particle levels differ from the requirements. The elements of the FMEA-Occurrence, Severity, and Detection-can identify the impact of different solutions on the process performance. Contamination control is a valuable tool for the development of complex systems where contamination is likely to limit the functionality or product quality and yield. The earlier the contamination risks are taken into consideration during the development, the better they can be counteracted.