What is the WOS ATD GC MS technique and when is it used?

The WOS (Wafer Out-gassing System) technique coupled with ATD GC MS (thermal desorption / gas chromatography / mass spectrometry) is an advanced method for detecting low-volatility or non-volatile contaminants, including condensables and organophosphorus compounds, deposited on surfaces. Six-, eight- or twelve-inch wafers are exposed in a cleanroom for several days and then sent to the laboratory for outgassing and analysis. The technique is used particularly in microelectronics to diagnose surface-contamination issues.