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A Tale of Two Fabs (continued)

Although minienvironments can maintain ISO Class 1 or Class 2 requirements, there are moments when the environments allow particle ingress. These moments include preventative maintenance (PMs), failures in fan-filter units (FFUs), improperly balanced dampers within the minienvironments, or particle transfer from contaminated Front Opening Unified Pods (FOUPs). If the cleanroom adopts more lenient ISO Class 6 (Fed. Std. 209E Class 1000), these particles will find their way into the minienvironments.

When promised the virtues of minienvironments, 300mm-semiconductor manufacturers should not be so eager to lower cleanroom gowning protocols. Minienvironments certainly improve processes and yields, but still, the cleanroom’s primary source of contamination is cleanroom personnel. If personnel adopt less stringent gowning protocols, we increase the sources and concentrations of contamination. Since current manufacturing technologies cannot remove personnel from the fab, we should make certain we remove the contamination that personnel bring into the fab. Following strict cleanroom gowning techniques and policies will help maintain high wafer yields and improve our industry.

Steve Kochevar
Applications Engineer
Particle Measuring Systems

Originally printed in an industry publication:
The Bartlett Bay Newsletter--December 2004