Airborne molecular contaminations (AMCs) represent a wide range of gaseous contaminants in cleanrooms. Due to the unintentional nanoparticle or haze formation as well as doping caused by AMCs, improved monitoring and controlling methods for AMCs are urgent in the semiconductor industry. However, measuring ultra-low concentrations of AMCs in cleanrooms is difficult, especially, behind a gas filter. In this study, a novel detection method for AMCs, which is on-line, economical, and applicable for diverse AMCs, was developed by employing gas-to-particle conversion with soft X-ray, and then measuring the generated nanoparticles. Feasibility study of this method was conducted through the evaluations of granular-activated carbons (GACs), which are widely used AMC filter media. Sulfur dioxide (SO2) was used as an AMC for the feasibility study. Using this method, the ultra-low concentrations of SO2 behind GACs were determined in terms of concentrations of generated sulfuric acid (H2SO4) nanoparticles. By calculating SO2 concentrations from the nanoparticle concentrations using empirical correlation equations between them, remarkable sensitivity of this method to SO2 was shown, down to parts-per-trillions, which are too low to detect using commercial gas sensors. Also, the calculated SO2 concentrations showed good agreement with those measured simultaneously by a commercial SO2 monitor at parts-per-billions.
Bibliographical noteFunding Information:
The University of Minnesota thanks the support of members of the Center for Filtration Research: 3 M Corporation, BASF Corporation, Boeing Company, Cummins Filtration Inc., Donaldson Company Inc., Entegris Inc., Ford Motor Company, H.B. Fuller Company, Mann + Hummel GmbH, MSP Corporation, Samsung Electronics Co., Ltd, Shigematsu Works Co., Ltd, TSI Inc., and W. L. Gore & Associates, Inc., Xinxiang Shengda filtration Technology Co., Ltd and the affiliate member National Institute for Occupational Safety and Health (NIOSH). The IUTA test system for toxic gases was funded by the federal state government of North Rhine-Westphalia in the framework of the Center for Filtration and Functionalized Surfaces (ZF). The financial and technical support is gratefully acknowledged. 3
© 2015, Springer Science+Business Media Dordrecht.
- Airborne molecular contamination (AMC)
- Environmental and health effects
- Gas-to-particle conversion
- Granular-activated carbon (GAC)
- Semiconductor manufacturing
- Soft X-ray