Michel Aliman

Very sensitive real-time inline process mass spectrometer based on FFT Ion Trap technique

In this work, we introduce a new, very fast and extremely sensitive inline process mass spectrometry technique based on Fourier-Transform 3D-Quadrupole Ion Trap technology. With this new technology, we have successfully detected sub-ppbV AsH3 and single digit pptV B2H6 dopants in H2 process gases within seconds. Real-time inline measurement at a CVD chamber showed that our technology was capable to detect reaction products, contaminations on the wafer holder and dopant memory effects in real-time. In contrast to typical residual gas analyzers, our new 3D-Quadrupole Ion Trap did not show mass discrimination with increasing m/z-ratio and was therefore capable to detect large molecules with very low concentrations.

High voltage RF generator and compensation network for a FFT ion trap mass spectrometer

In this work we present two electronic key components to operate a quadrupole ion trap mass spectrometer. Radio frequency high voltage generation is mandatory to create a trapping field. Our trap works in the Fourier transform mode, consequently very small induction currents have to be detected from the ion motion. Since interference signals from the storage voltage are many orders of magnitude higher than the detection signal, a sophisticated compensation circuit is required at the amplification stage.