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.

1. INTRODUCTION

Micropumps are an essential component of many microsystems for chemical and biomedical analysis. Countless approaches to realize miniaturized pumps have been pursued [3], , [5]. None of them is capable of generating a vacuum which meets the demands of miniaturized complex analytical instruments like micro-mass-spectrometers [1], [2]. In this paper a new approach to micro vacuum pumps is presented: Based on macroscopic vapor-jet and diffusion pumps, a miniaturized pump is designed, fabricated and characterized. The advantages of this pump mechanism and its miniaturization are: