Silicon microdischarge devices having inverted pyramidal cathodes: Fabrication and performance of arrays

Microdischarge devices having inverted, square pyramidal cathodes as small as 50 μm×50 μm at the base and 35 μm in depth, have been fabricated in silicon and operated at gas pressures up to 1200 Torr. For the polyimide dielectric incorporated into these devices (εr=2.9), the discharges produced exhibit high differential resistance (∼2×108 Ω in Ne), ignition voltages for a single device of ∼260–290 V, and currents typically in the μA range. Arrays as large as 10×10 have been fabricated. For an 8 μm thick polyimide dielectric layer, operating voltages as low as 200 V for a 5×5 array have been measured for 700 Torr of Ne. Array lifetimes are presently limited to several hours by the thin (1200–2000 Å) Ni anode.