Mass spectra measured by a fully integrated MEMS mass spectrometer

Breakthrough measurements of a single chip mass spectrometer are presented. This planar integrated micro-mass spectrometer (PIMMS) is dedicated for mobile measurements, portable applications as well as for continuous process monitoring.The waferbased fabrication in MEMS technology allows a very cost-efficient mass production. All critical structures are fabricated by a one mask anisotropic deep silicon etch, avoiding alignment difficulties. The small size (5mm×10 mm) reduces the vacuum requirements by several orders of magnitude, thus a one stage pumping system can provide the necessary vacuum. The operation is based on electron impact ionization and a synchronous ion shield mass filter.The electron beam for ionization is supplied by a source, that extracts electrons from a high density microwave plasma. The integrated ion optics extract and focus the beam into the mass separator, where time variant electric fields separate the ions according to their mass-to-charge ratio. An energy filter ensures that the ion beam is monochromatic before it is finally recorded at the detector.The accomplished experiments prove the concept of the fully integrated mass spectrometer on a chip. Mass spectra of different gas compositions measured with the PIMMS are presented.