UV-Induced Polytetrafluoroethylene Degradation as a Source of Particulate Contamination in Pure Water Systems
By Michael Green and Timothy Strodtbeck
The advent of copper integrated circuits in semiconductor manufacturing in the late 1990s led to the need for an efficient, environmentally compliant way to remove copper from wastewater generated from copper chemical mechanical planarization/polishing (CuCMP) processes. CuCMP chemistry involves oxide slurry solids, chelators and other components that complicate traditional precipitation wastewater treatment methods that create a waste solid (i.e., sludge) considered to be hazardous waste by federal and state environmental regulations.
To meet this need, an alternate CuCMP wastewater treatment system was developedA, using selective ion-exchange (IX) resin to remove copper and allow for its recovery. This treatment system was commercializedB in the early 2000s and has been successfully used to treat CuCMP wastewaters in the United States, Europe, and Asia.
Manufacturing processes for solar photovoltaic devices (i.e., solar cells) use chemistry with characteristics similar to those of CuCMP, and continued development of the treatment system has extended its use to solar cell manufacturing wastewater. Table A shows the typical composition of wastewater from CuCMP and solar cell manufacturing processes.
This article focuses on the primary components of the CuCMP treatment system— specialized activated carbon and selective IX resin— and discusses methods for choosing and optimizing these components for best performance in treatment applications.
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