POREX® Tubular Membrane Filter Modules for CMP Wastewater Reclamation
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Background
Chemical mechanical planarization (CMP) has been the preferred planarization process in wafer fabrication (Fab) since it was developed in 1985. However challenges arise with CMP because polishing slurry is applied and a large quantity of ultrapure water (UPW) (sometimes reaching 15~40% of total UPW consumption) is used for flushing which generates equally huge amounts of wastewater. In the past, a conventional treatment process including pH adjustment, coagulant feeding, flocculent feeding, and sedimentation was selected to treat wastewater to reach the discharge standard. Due to the CMP wastewater characteristics, this treatment would consume large amounts of coagulants and flocculants. As a result, a large volume of sludge was produced and needed to be treated further, increasing the operating cost and raising environmental issues as well. Because of these increased operating costs and environmental concerns, many semiconductor Fabs are turning to membrane technology to treat CMP wastewater. The treated CMP wastewater can then be tested for compliance as recycled water for internal facility use or discharge to drain. |