Planar-processed tungsten and polysilicon vacuum microelectronic devices with integral cavity sealing

Abstract

Solid-state micromachining and planar lithography have been applied in the formation of vacuum microdiode devices. These devices are fabricated with an on-chip vacuum cavity through directional material sealing techniques initiated at vacuum pressure of ∼2×10−6 T. Both tungsten and polycrystalline silicon have been used as cold-cathode emitter materials. The resulting current–voltage characteristics are stable and show good Fowler–Nordheim characteristics to operating currents in excess of 50 μA for wedge-shaped emitter tips. Electrical noise measurements carried out indicate a dominance of flicker noise at low frequencies for both tungsten and polycrystalline silicon microdiodes with the tungsten devices exhibiting excellent characteristics.