Measurement of arsenic and gallium content of gallium arsenide semiconductor waste streams by ICP-MS

The chemistry of semiconductor wafer processing liquid waste, contaminated by heavy metals, was investigated to determine arsenic content. Arsenic and gallium concentrations were determined for waste slurries collected from gallium arsenide (GaAs) wafer processing at three industrial sources and compared to slurries prepared under laboratory conditions. The arsenic and gallium content of waste slurries was analyzed using inductively coupled plasma mass-spectrometry (ICP-MS) and it is reported that the arsenic content of the waste streams was related to the wafer thinning process, with slurries from wafer polishing having the highest dissolved arsenic content at over 1,900 mgL−1. Lapping slurries had much lower dissolved arsenic (< 90 mgL−1) content, but higher particulate contents. It is demonstrated that significant percentage of GaAs becomes soluble during wafer lapping. Grinding slurries had the lowest dissolved arsenic content at 15 mgL−1. All three waste streams are classified as hazardous waste, bas...