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Guide to Evaluate the Efficacy of Sub-15 nm Filters Used in Ultrapure Water (UPW) Distribution Systems

SEMI C79, initially released in 2013 and updated in 2019, has become an industry standard for measuring the cleanliness and retention performance of UPW filters for advanced node semiconductor manufacturing.  This method was developed and validated by CT Associates in collaboration with SEMI™ and the SEMI UPW Task Force.  

Cleanliness of the filter and flush volume-to-quality is measured with online instruments including optical particle counting (Figure 1), Scanning Threshold Particle Counting (STPC) (Figure 2) and organic concentration (Figure 3). 

The method utilizes a silica mixture with particle size ranging from 6 to 35 nanometers.  Retention capacity of the filter is measured using liquid nanoparticle sizing (LNS), a liquid-based particle sizing and counting technique developed by CTA (Figure 4).  

As developer of this method, CT Associates is in a unique position to conduct this specialized test method.

Figure 1 - Filter Cleanliness by OPC

SEMI C79 filter cleanliness by OPC

Figure 3 - Filter Cleanliness by TOC Analyzer

SEMI C79 TOC Rinse

Figure 2 - Filter Cleanliness by STPC 

SEMI C79 Rinse performance by Kanomax FMT Scanning threshold particle counter stpc

Figure 4 - Filter Retention by LNS

SEMI C79 filter Retention by LNS liquid nanoparticle sizing
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