Treatment of Cu-Cmp Waste Streams Containing Copper (II) Using Polyethyleneimine (Pei)
Worawan Kay Maketon and Kimberly Ogden. Department of Chemical and Environmental Engineering, University of Arizona, P.O. Box 210011, Tucson, AZ 85721-0011
The use of copper in the semiconductor industry is increasing due to copper's lower electrical resistance value in comparison to aluminum, which provides a number of performance advantages. A copper-based chip may need only half as many metal layers as one made with aluminum, because copper has superior properties which provide considerable reduction in manufacturing cost. The copper chemical mechanical planarization process (Cu-CMP) is a critical step that is repeated several times during the production of a single wafer. The incorporation of copper in integrated circuit metallization had resulted Cu-CMP and post-CMP cleaning waste streams that contain copper nitrate concentration, silica particles as an abrasive, complexing agents, surfactants and some source of organics. This study explores the use of polyethyleneimine (PEI) bound with crosslinked and activated agarose gel, NovaroseTM, for waste treatment. A model Cu-CMP wastewater, containing copper (II) solution, was developed and tested. PEI-agarose adsorbent has been investigated in both batch and continuous flow column experiments. The results showed PEI-agarose was efficient at binding copper from CMP wastes. PEI-agarose adsorbent can be regenerated, allowing the copper to be recovered from the wastewater. Moreover, the adsorbent stability is good. It can be regenerated over and over again numerous times.