High-voltage constraints for vacuum packaged microstructures

In order to understand the details of high-field breakdown in microstructures that are vacuum packaged, a series of experiments are used to determine characteristics of microdischarges. The results support a reinterpretation of conventional assumptions based upon large scale discharges. When planar microelectrodes are used, Paschen's curve is not applicable in the traditional sense: the breakdown voltage is relatively insensitive to pressure in the 1-20 torr range, and remains at ∼400 V for air ambient. However, the spatial distribution of discharge current does vary with the pressure and the power. Large voltage gradients are supported in the glow region which is confined to a few millimeters directly above the cathode, and within a few hundred microns of its lateral edge. Their magnitudes range from 100,000-500,000 V/m for operating pressures ranging from 1.2-6 torr. Based on these results, guidelines are provided for the design of high-voltage microsystems.