A MEMS electron impact ion source integrated in a microtime-of-flight mass spectrometer

An electron impact ion source has been fabricated using MEMS technology. The chosen fabrication process allows for manufacturing simultaneously and collectively the ion source and the analyser on the same substrate. A small and compact micro time-of-flight spectrometer is thus structured in a monolithic way in large scale integration (LSI). The fabrication process and the performances of the source, based on the electron impact ionization mechanism, are presented. The ion current can be as high as tens of nano-amps, one of the highest level reported for an integrated source in a micro mass spectrometer. It presents a raw ionization efficiency of 2.5 × 10−3. By positioning a fast detector at a few millimeters from the ion source, a simple linear TOF mass spectrometer has been assembled. Promising spectra have been obtained on simple gases like argon.