Study of dc micro-discharge arrays made in silicon using CMOS compatible technology
Résumé
In this paper we present the fabrication technology used to make micro-discharge 'reactors' on a silicon (Si) substrate. For the fabrication of these reactors we have used Si wafers with 4 inch diameter and standard cleanroom facilities. The fabrication technology used is compatible with standard CMOS device fabrication and the fabricated micro-discharge reactors can be used to produce dc discharges. These micro-discharges operate at near atmospheric pressure. They were given ring-shaped anodes separated from the cathode by a SiO2 dielectric with a thickness of approximately 5-6 μm rather than the much more common ∼100 μm. The micro-discharge reactors can consist of either a single hole or multiple holes and we have built devices with holes from 25 to 150 μm in diameter. The micro-discharge measurements were obtained for helium and argon dc plasmas between 100 and 1000 Torr. We used a single ballast resistor to produce micro-discharges in multi-hole array. This resistor also acted to limit the discharge power. An average current density of 0.8 A cm−2 was calculated for the 1024 holes array with 100 μm diameter holes. In addition, we will report on stability of micro-discharges depending on the cavity configuration of the micro-reactors and the ignition trends for the micro-discharge arrays. Finally, we discuss the life time of micro-discharge arrays as well as the factors affecting them (cathode sputtering, thermally affected zones, etc).