Removal of 12-nm Particles from High-purity Water by a Combination of Ultrafiltration and Microfiltration
A particle detection technique has been developed that enables filter manufacturers to measure retention efficiency for small, critical particle sizes <50nm in the laboratory environment. This method has been employed to evaluate the filtration performance of ultrafiltration filters typically employed in most UPW systems today. The testing demonstrates that although these ultrafilters have high retention efficiency, some of these very small particles can still pass through and create a risk for the semiconductor manufacturer. This test method was further used to show that a very high retention microfilter is able to retain a large fraction of the small particles as well. Finally, it was validated that an overall filtration system using both an ultrafilter and a high retention microfilter in series shows superior retention performance for particles as small as 12 nm.
Published by: Ultrapure Water Journal, May/June 2012, ©Tall Oaks Publishing
Authors: Don Grant, CT Associates, Inc.; Uwe Beuscher, W.L. Gore & Associates, Inc.