Wastewater recycling system addresses environmental concerns

02/01/2000

NEWBURY, OHIO -The STMicroelectronics (Phoenix, Ariz.) wafer fab has begun operation of an integrated wastewater recycling system designed and built by Kinetico Inc. (Newbury, Ohio). The system uses propritary recycling technology and is believed to be the first integrated water recycling system installed in the U.S. semiconductor industry for chemical mechanical planarization (CMP), metal, oxide and backgrinding process wastewater.

The system is capable of recycling 40 million gallons annually of semiconductor/CMP wastewater and addresses several environmental concerns, including water consumption from the CMP process, future discharge regulations for copper CMP and removal of high volumes of suspended solids from wastewater.

The crossflow microfiltration system treats the combined wastewater from CMP and backgrind processes and removes the suspended solids through the formation of a filtering layer built and composed of the wafer particles deposited on an abrasion-resistant, proprietary polyester membrane. The wastewater is then sent to the recycling system, which recycles water at more than a 90 percent recovery rate and then returns it to the CMP ultra pure water (UPW) loop. The system provides good water recovery, lower reject waste volumes and higher purity water from wastewater streams containing high concentrations of dissolved silica. The system resolves the critical membrane fouling issues common to streams containing high levels of silica.