Microfabricated Quadrupole Ion Trap for Mass Spectrometer Applications

An array of miniaturized cylindrical quadrupole ion traps, with a radius of 20 � m, is fabricated using silicon micromachining using phosphorus doped polysilicon and silicon dioxide for the purpose of creating a mass spectrometer on a chip. We have operated the array for mass-selective ion ejection and mass analysis using Xe ions at a pressure of 10 � 4 Torr. The scaling rules for the ion trap in relation to operating pressure, voltage, and frequency are examined.