Using fluorescent labeling of bacteria instead of the Filter membrane culture method to monitor bacteria in semiconductor equipment

This paper describes the sampling methodology, the benefits and lessons learned converting a semiconductor fab's ultrapure water (UPW) bacteria testing procedure to a process with a faster turn-around time. The fab went from using a Filter membrane culture method (FMC) for monitoring the bacteria in the ultrapure water (UPW) of process equipment to using the fluorescent labeling method using laser scanning cytometry (LSC). The new procedure was as good or better than the previous procedure although at a slightly higher cost. Several examples illustrate its use in releasing newly installed equipment to production and in troubleshooting bacteria contamination problems.