Mass-Spectrometric Detection of Low-Ppm Contaminants in Sputter Process Systems at 10-2 Mbar, Using a Directly Exposed Ion-Source

Trace contaminants in sputter atmospheres (10(-2) mbar Ar) are determined with a mass spectrometer whose ionizer is directly exposed to the process pressure, whereas the quadrupole filter is kept at high vacuum. The background limitations inherent to conventional differentially pumped analyzers are overcome. Detection limits are 1 ppm for H2O and few ppb for other species.