I. Introduction
Airborne Molecular Contamination (AMC) can cause serious impact on semiconductor manufacturing process. In cleanroom, once the AMC level is detected OOC (out of control), the source must be identified and be removed as soon as possible to reduce process impact. The AMC OOC may be caused by sources from both outdoor environment and cleanroom inside. The source from outdoor can be easily identified by monitoring make up air contamination level, and be treated with air treatments like air washer and chemical filters. On the contrary, the source from inside, due to airflow circulation and contamination dispersion, is more difficult to identify when the AMC is detected. In current practice for cleanroom AMC control, the AMC level is measured routinely via the monitoring system as in Fig-1. When the AMC level is detected OOC at a sensor point, and then the cleanroom management must:
Check the nearby environment to find AMC source and remove it. This will partly base on the engineer's experience.
If the action-1 fails: by try-error, re-arrange more measurement points with wider range around the OOC sensor point, sample and analyze environment air. Based on analysis result, find the AMC source and remove it.
If it fails again: adjust the measurement area and density, and repeat the procedure again until the AMC source location is identified and removed.