A Micromachined Vapor-Jet Vacuum Pump

A MEMS vapor-jet pump for vacuum generation in miniaturized analytical systems, e.g. micro mass-spectrometers, is presented. A high velocity nitrogen- or water-vapor-jet is used for vacuum generation. Starting from atmospheric pressure, a high throughput of more than 50 ml/min and an ultimate pressure of 495 mbar were obtained with this new type of micropump. An approach for the full integration of all components of the pump is presented and validated by experimental results. The pump is fabricated from silicon and glass substrates using standard MEMS fabrication techniques including DRIE, trichlorosilane MVD and metal-assisted chemical etching for porous silicon fabrication. Micromachined pressure sensors based on the Pirani principle have been developed and integrated into the pump for monitoring.