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Identification and Management of Potential Particle Precursors from Mixed Bed Ion Exchange


Larry Zazzera, Gary Van Schooneveld - CT Associates, Inc.
Stefan Huber - DOC-Labor GmbH
Bonnie Marion - FTD Solutions


Organic contamination present in Ultrapure Water (UPW) poses a risk of depositing on the wafer surface during processing and cleaning. Organic contaminants include a range of chemical functionality in the form of small molecules, oligomers, and polymers. The chemistry and size of the organic contaminants influence their behavior in UPW systems, their potential for deposition, and the nature of films and particles on the wafer surface.

To aid the industry in mitigating the risk of these contaminants, the SEMI UPW Task Force is developing a particle precursor challenge, specifically ion exchange resin extract, for inclusion in SEMI C79, Guide to Evaluate the Efficacy of Sub-15 nm Filters Used in Ultrapure Water (UPW) Distribution Systems. Past experimental work by the UPW IRDS team demonstrated that compounds leached from ion exchange resin extract can form particles on a wafer. Ion exchange resin extract is organic by nature; therefore, characterization of organics in the extracts is a prerequisite to developing and validating challenges that can be used in a variety of methods to monitor the UPW ecosystem.

The objectives of this study are to characterize organics in ion exchange resin extracts, document the reactivity (stability) of these species, and to compare these results to contaminants in UPW. These findings will guide the development of a particle precursor challenge protocol for purification devices and provide basic chemical and physical property data of organics in UPW. This new account of organics in UPW is important because it will enable better monitoring and improved control of potential particle formation on wafers.

CTA publication #151: Ultrapure Micro 2023 Conference, San Marcos, TX, 2023.

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