Ultra-high Cleanliness of ISO Class Minus 2 Realized by Clean-Unit System Platform for Integrating the Bottom-up and Top-down Systems

Abstract

The time dependence of the airborne particle count and the cleanliness of an airtight stainless steel clean-unit system platform (S-CUSP) with 100% air feedback through the feedback loop by installing the ultra low penetration air (ULPA) filter just beneath the high efficiency particulate air (HEPA) filter in the feedback loop has been studied. By controlling the number of particles coming out from the HEPA filter, the ultra high cleanliness of ISO class minus 2 has been obtained, which is five orders of magnitude better than that of the super cleanroom (ISO Class 3). Analyses of the experimental results demonstrate that the S-CUSP with flat feedback loop would be a viable economical means to achieve the more stringent cleanliness class, which has the immense importance for expediting the multi-disciplinary experiments and production fields such as nanotechnologies and biotechnologies.